My dissertation write up on the geology of Bheinn Shuardail, Isle of Skye, Scotland. I am proud of this work as this gained a first class grade.

1. A REPORT ON THE GEOLOGY OF BHEINN SHUARDAIL, ISLE OF
SKYE, SCOTLAND
OWEN RHYS GREENING
201088122
17/18
A dissertation
Submitted to
The University of Liverpool
in partial fulfilment of the requirements
for the degree of
Master of Earth Science

2. Abstract
The Isle of Skye is an island present in the Inner Hebrides with a rich geological history associated
with it. Skye contains exposure of rock units from Pre-Cambrian Torridonian up to Palaogene Igneous
complexes that are present in across the island. A range of sedimentary units have been deposited on
the Southern end of Skye, South of Broadford: These units include massive sandstones that are mostly
featureless, dolomitic limestones with siliceous impurities, a polymictic conglomerate with a wide
range of maturity through the unit, a limestone with interbedded mudstones and a high shell content, a
sandstone with mudstone interbeds that contain Gryphaea fossils within the mud layers as well as a
fissile shale unit containing similar fossil content.
There has been deformation within the area with two units hosting an antiform caused by the intrusion
of a granite pluton as well as a synform in the younger strata. The younger units have also been
faulted that run on a North-South trend.
There has been extensive igneous activity around Bheinn Shuardail. The largest igneous feature is a
boss-shaped Kilchrist Granite that consists of mostly granite and has had a profound effect on the
country rock it has intruded into. Other igneous features such as dykes and sills of various
compositions as well as a larger intrusive feature with a rhyolitic/ andesitic composition.
There has been alteration of the siliceous impurities within the Bheinn Shuardail Limestone that has
resulted in the production of Talc, Tremolite and Forsterite within the mineral assemblages of the
zones of contact metamorphism. This heat addition and fluid movement has also resulted in mineral
precipitation of skarn material on the outside of the pluton.
Acknowledgements
There are a plethora of people who have helped me complete this project. I would like to thank the
department especially the staff running ENVS269 and ENVS351 for teaching me the techniques
needed to complete this project. I would also like the thank John Wheeler for guidance given prior to
and during the project work between the 28th
of June and the 6th
of August. Finally, I would like to
thank Rebecca Williams, Emily Collier, Robyn Tate, Alex Simpson and Emily Vickers for their
support whilst on Skye. My supervisor Felix Von Aulock was also a great help to me, he was
approachable and useful throughout the whole write-up process.

3. CONTENTS
Chapter 1 - INTRODUCTION
2 1.1 Location of Bheinn Shuardail
3 1.2 Geology of the area
5 1.3 Report structure and data summary
Chapter 2 - STRATIGRAPHY AND PALAEOENVIRONMENT
7 2.1 Cnoc na Cubhaige Sandstone Formation
11 2.2 Bheinn Shuardail Limestone Formation
15 2.3 An Coire Conglomerate Formation
22 2.4 Allt Tarsuinn Limestone Formation
29 2.5 Druim Bhain Sandstone Formation
34 2.6 Heaste Shale Formation
Chapter 3 - METAMORPHIC ACTIVITY AROUND BHEINN
SHUARDAIL
37 3.1 The effects of contact metamorphism on the Bheinn
Shuardail Limestone caused by the intrusion of the Kilchrist
Granite
48 3.2 The formation of skarn material around the granite pluton

4. Chapter 4 - IGNEOUS ACTIVITY
49 4.1 The Kilchrist Granite pluton
52 4.2 Small-scale igneous rock formations
Chapter 5 - STRUCTURAL FEATURES
55 5.1 The Bheinn Shuardail antiform
56 5.2 The Druim Bhain synform
57 5.3 Other structural features
Chapter 6 - GEOLOGY HISTORY OF BHEINN SHUARDAIL
(CONCLUSIONS) 58
Chapter 7 - REFERENCES 59

5. 1
Chapter 1 - Introduction
The Isle of Skye is the largest island within the Inner Hebrides and is also the most Northermost of the
major British islands. Skye has been separated from the mainland by Loch Alsh with the island
accessible by road in the form of a bridge across the water.
The topography of Skye varies wildly, the centre of the island is dominated by the Cuillins. There are
the Black Cuillins that are made up of Basalt and Gabbro as well as the Red Cuillins that have a
Granitic composition. The rest of the landscape is also covered in marshes, peat bogs and mostly
grassland with very high exposure to the elements.
There have been a great number of studies undertaken on the Isle of Skye with almost every aspect of
the island having literature associated with it. There have been geological studies published as far back
as 1891 into the Tertiary Igneous complexes on Skye (Harker 1891).
Igneous rocks on Skye are in contact with the old Torridonian sediments that have been deposited and
then subsequently metamorphosed. The coarse grained complexes are likely part of a larger volcanic
superstructure but did not reach the surface and become extrusive volcanics (Emeleus, Bell et al.
2005).
The mapping area around Bheinn Shuardail is located on in the Strath area of Skye. Strath has a low
population with only a handful of villages placed around. Accessibility of my mapping area was poor
with only a few paths present that lead to a number of lochs such Loch Buidhe and Loch Lonachan.
The areas without paths were difficult to traverse and the peat bogs made fieldwork incredibly
difficult. Rivers cut the area into sections and other methods had to be employed to reach the areas to
be studied on certain field days. Allt Ghleann Shuardail was the most problematic as the depth of the
valley and the water itself made it impossible to access Bheinn Shuardail without using a car to drive
through Broadford and onto the far side of the hill.
Exposure of the geology was also an issue as the vegetation covered most of the units. Vegetation was
useful in following the contacts between different units as certain plants grew on certain rock types.
Some units were better exposed than others and human activity was useful in allowing me to make
observations. Good examples of this are the various quarries dug into the hillside of Bheinn Shuardail
and the rock that has been cut away to make room for the road linking Harrapool and Heaste.

6. 2
1.1 Location Maps for the area I completed my project work:

7. 3
1.2 Geology of my mapping area:
Map

8. 4
Generalised Vertical Section:

9. 5
Cross-sections:
1.3 Report Structure and Data Summary:
This contents page is indicative of how this report will be structured. This report is split into different
sections based on rock family as well as some other aspects such as structural geology. The rock types
and events that have occurred are arranged in date order from oldest to youngest.
All data was collected in a systematic manner during three phases of the projects: During the
reconnaissance phase, mapping phase and the phase that involved more detailed work into aspects
such as palaeoenvironment or mineralogy.

10. 6
1.4 Methodology:
The fieldwork was completed in three phases. Some phases lasted different lengths to others. Firstly,
there was the reconnaissance phase followed by the mapping phase and finally the phase of more
detailed work on the different facets of the geology.
Phase 1: Recon
The reconnaissance phase was first demonstrated in ENVS269, this gave a very much brief insight
into the general aspects of the area. Examples of this included features like:
 Topography
 Basic rock units features (Example, Colour)
 Prelude to mapping (Example, drawing basic contacts vaguely and low resolution)
 Vegetation change
 Recording basic data (Example, occasional orientation datum)
Reconnaissance only lasted a week but was vital in gaining an understanding of the geological
situation as well as allowing a plan to be formulated on how to tackle the area over the coming weeks.
Phase 2: Mapping
Mapping was the primary purpose of ENVS269 and lasted for a duration of two weeks during the
month of July. This phase did not involve much reliance on the field notebooks to record data but
instead data was transferred directly onto the 1:10000 map, allowing for greater accuracy and
precision. Ground was covered quickly and efficiently in comparison to the other two phases,
especially phase three. Once the units were covered in sufficient detail and the map was fully
completed, phase three began.
Phase 3: Advanced field work
Phase three involved the utilisation of techniques acquired in ENVS351. Primarily, the aim for this
phase of the fieldwork was to move into more detail as to different features of the geology present and
consequently involved the greatest use of the field notebooks. Data gathered allowed for more in depth
analysis of features such as palaeoenvironment, formation history and such like. Finally, a couple of
days were spent at the end of the allotted time period to overview the mapping area as a whole and fill
in any gaps that were missed over the course of the 35 days.

11. 7
Chapter 2 - Stratigraphy and Palaeoenvironment
Six distinct sedimentary formations have been identified running through the mapping area. The
formations progress roughly in age order from the North West into the South-East with the formations
forming in a mostly linear fashion on a North-South trend.
2.1 Cnoc na Cubhaige Sandstone Formation
The Cnoc na Cubhaige Sandstone Formation is the oldest rock unit in the area. The unit outcrops
mainly in the centre of the mapping area and extends from the furthest South up to the North. CCS
also outcrops onto the Northern face of Bheinn Shuardail. The CCS has the largest exposure problem
out of all the units, the rock only outcrops at a select few places in the centre of the map. Exposure
was only prevalent towards the North or where the rivers have eroded downwards and exposed the
cliff sides. Most of the unit was covered in peat bogs and vegetation.
2.1.1 Observations
The CCS unit was grey in colour when a fresh surface was located but most of the unit had been
weathered into a red colour. The grains were medium grained 250-500μm in the vast majority of beds
with sub-rounded grains that were well sorted. Feldspars made up roughly half of most samples with
orthoclase/ plagioclase relative abundance at ~50%. Quartz abundance was steady at ~20% with lithic
fragments making up most of the remainder (~30%). Mineral abundances lead me to conclude that the
CCS is an arkosic arenite. CCS itself is a clean sandstone (lacking any muddy component). The
overall texture of the sandstone is sub-mature as well as the mineralogy with the presence of feldspars.
Sedimentary structures within the CCS are few and far between. The unit is massive without many
bedding planes or distinct changes between beds. Cross stratification and lineations are the most
common structures nevertheless they are only present in select beds and are small in size (typically
only a few centimetres).

12. 8
At the top of the CCS unit there are extensive linear
features that are extremely numerous and cover most
of the bedding surface. The features seem to have no
distinct overall orientation nor do they seem to
interact with the rest of the unit in a meaningful way.
There are two competing theories as to the origin of
these planar lines. The first theory is that they are
mineral veins that have formed through the influx of
hydrothermal fluids into extensional cracks within
the sandstone itself. Cracks of this nature could have
been caused extensional forces pulling apart the
sandstone. Silica rich fluids then percolate into the
rock and the quartz precipitates out. A second theory
as to the origin of these features is that they are
compaction bands. Compaction bands are narrow
planar zones of localised purely compressive
(without shear) deformation that form perpendicular
to the most compressive principal stress (Issen and
Rudnicki 2001). Any definitive conclusion is
difficult as either of these hypothesis would involve
stresses acting in a number of different directions rather than one larger deformation event. It is
difficult to ascertain a certain theory.
Figures 1 + 2: Images of the features at the top of the sandstone unit. Note in figure 2 how they
meet to form distinctly shaped protuberances. (GR821200,164600)

13. 9
The stereonet above shows the veins intersect each other with a general trend of South-West across the
rock face.
2.1.2 Interpretations
There are various factors about the sandstone that has led to a solid conclusion on the environment that
the CCS was deposited in. The presence of feldspars within the arkose indicates that the opportunities
for chemical weathering of the sandstone were limited so feldspars were able to become part of the
mineral composition. An environment in which such limited weathering occurs must be cold/ arid or
the sediment has been deposited rapidly. A textbook example of such processes would be in a fluvial
environment, rivers would be ideal for producing the cross stratification and lineations that are present
as well as depositing the sediment fast enough to preserve the feldspathic elements of the unit. In
conclusion, the CCS is the product of a terrigenous area with a fluvial system. This can further be
supported by a lack of fossils.
Figure 3: Stereonet of the orientations of the veins plotted as planes.

14. 10
Figure 4: A sedimentary log for the CCS unit. A key for the symbols can be found on the loose material.

15. 11
2.2 Bheinn Shuardail Limestone Formation
The Bheinn Shuardail Limestone formation is the
second oldest rock unit in the mapping area. The unit
outcrops in the North-Western section of my mapping
area. The limestone is the primary rock that makes up
the composition of Bheinn Shuardail, the 281m high
hill. Exposure of the limestone is slightly better than
the CCS and there is a distinct change in vegetation
between the two units, BSL having much more
plentiful vegetation as well as more ferns. The
weathered sides of the hill provide some of the best
exposure as well as some of the quarried areas at the
base of the hill. Palaeokarstic surfaces are present on
top the unit in the form of solution channels (figure 5)
and sinkholes. Sinkholes posed a safety hazard as
vegetation grows over the top, obscuring them
entirely.
2.2.1 Observations
The BSL formation is uniform in lithology. The limestone unit has noticeable calcite spars with minor
micrite aspects to the rock. The outside of the rock surface has been weathered to a darker grey than
the lighter grey fresh surfaces found where the limestone has not been exposed to the environment.
There are select few features of the BSL. Mineralisation is evident on the surface of the rock unit, the
mineral forms distinct banding across the limestone. The bands are harder than the rest of the rock
with a hardness of 4 and a slightly lighter colour. This mineral was identified to be dolomite. Dolomite
does not make up over 75% of the composition so there was no need to call this rock a dolostone
(Machel 2003).
Figure 5: Solutions channel (form through acid
dissolution) on top of the BSL unit with arrows for
water flow direction (2 shilling piece for scale).

16. 12
A distinguishing feature of the BSL is the presence of
the various chert nodules and chert bands that are
present throughout a select zone of the BSL. These
siliceous impurities produce some spectacular results
when subject to heat, this will be explored further in
chapter 3. Chert is silica and therefore extremely hard
(7 hardness), this results in the nodules and bands
protruding very clearly out of the much softer dolomitic
limestone. Figures 6 and 7 are examples of the
unaltered chert features that are found throughout the
unaltered zones.
Figure 6: Example of unaltered chert nodules in
the limestone.
Figure 7: Chert banding. The bands may have formed as seen here or are the result of
multiple chert nodules forming in a linear fashion.

17. 13
2.2.2 Interpretations
The dolomitic limestone was deposited initially in a warm, shallow tropical sea environment with a
slighter stronger current hence the calcite spars. The dolomite bands have been formed from chemical
change post deposition. Dolomitisation occurs from the reaction of sea water with the existing calcite
within the limestone. The sea water must have a marine source and for extensive dolomitisation to
take place there must be a steady supply of sea water over time. Flow of fluid could have been
facilitated by a geothermal heat source (Hairuo and Mountjoy 1992). The process has not been
extensive as the rock is not a full dolostone.
The origin of chert within the limestones have a
similar source. Fluid movement produces a
dissolution of the calcite minerals. This leaves
the silica saturation of the waters much higher
with the origin of the silica from the secretions of
sponges as well as the skeletons of radiolarians as
well as diatoms. The chert nodules formed from
the recrystallisation of individual organisms
providing a nucleation site for the nodule to form
from diagenesis. Chert bands form from the
compaction and recrystallisation of siliceous ooze
deposits that exist on the seafloor in deeper
waters. The lack of fossils found within the
dolomitic limestone is supported by the theory of
chert formation, as the chert forms around
nucleation.
Figure 8 (above): 4 possible explanations
for the process of dolomitisation. (Nichols
2009), originally from (Tucker and Wright
1990)

18. 14
Figure 9: Above is a diagram for the formation of both the chert bands (Scenario 1) and chert nodules
(Scenario 2). Edited for this particular situation, original from (Rasmussen, Meier et al. 2013).

19. 15
2.3 An Coire Conglomerate Formation
The An Coire conglomerate formation is a sedimentary rock unit that is the next youngest in the
stratigraphy of the area. Using lithostratigraphy, the conglomerate is placed in the New Strath Group
as part of the units that come after a significant gap in time from the Bheinn Shuardail Limestone.
Exposure of the unit is poor and crops out in a roughly linear fashion on a North-South trend through
the central part of the mapping area. Exposure is the best in the South and represents clear lithological
changes over distance. The matrix and clasts of the conglomerate changes throughout the unit which
provided good data for analysis.
2.3.1 Observations
Different sections of the unit show clear
changes throughout. At the base of the
conglomerate, the unit is the most similar to
the CCS unit. The groundmass of the unit is
lithologically very similar with the same
mineral make up (of mostly feldspars) as
well as weathering that has turned the unit
red. Firstly, the base of the unit is
monomictic in nature and only contains
quartz pebbles within it at random
orientations. The quartz pebbles within the
conglomerate here could be intraformational
clasts freed by penecontemparenous erosion
of the CCS. Maturity of the conglomerate is
much better towards the base of the unit with
more equal sized pebbles (shown in figure
11) that are rounded/ sub-rounded in shape.
As we travel upwards stratigraphically, the
maturity of the unit decreases rapidly as will
be seen in this section.
Figure 10: Conglomerate bed at the base of the unit. Note the
red sandstone groundmass as well as the monomictic quartz
pebbles. (pebble size ~2cm)

20. 16
Figure 11: A histogram for the pebble size (X-axis) and pebble frequency (Y-axis) for the
bed at the base of the ANC unit. (GR164800,821350)
0
1
2
3
4
5
6
7
8
9
1mm 1-8mm 8-15mm >15mm

21. 17
Travel towards Loch Buidhe and the lithology of the
conglomerate changes considerably. The
composition of the conglomerate begins to change.
First and foremost the most prevalent change is the
composition of the matrix. This matrix is no longer
lithogically similar to the CCS unit having now
become a micrite mud matrix, giving the beds have
an overall grey colour rather than the corresponding
red. Secondly, the micrite beds are polymictic in
nature. Clasts in the micritic bed consist of dolomite,
sandstone, quartz as well as metaquartzite,
demonstrating a sub-rounded/ sub-angular shape.
Figure 12 (RIGHT): the
polymicitic
conglomerate bed with a
micrite matrix
Figure 13: A histogram for the pebble size (X-axis) and pebble frequency (Y-axis) for the
texturally somewhat mature micritic bed as shown in figure 12.
0
2
4
6
8
10
12
<10mm 10-30mm 30-50mm >50mm

22. 18
Further progress up the ANC unit begins to
demonstrate a change from bed to bed between the
micrite dominated matrix in comparison to the
sandstone dominated matrix. The general trend is
the increasing textural and compositional
immaturity towards the top of the unit. Clast size
through the beds also show evidence of grading
indicating that the unit is the right way up.
Figure 14 (right): another
image of the polymictic clasts
grading upwards

23. 19
At the Southernmost outcrop of the conglomerate
demonstrates the greatest compositional and
lithological differences from the lowest bed of the
unit. The clasts vary wildly in size with no clear
pattern of grading or other sedimentary structures.
This conglomerate bed is so lithologically
immature that the unit has many properties
expected of a breccia. There is no distinct pattern
between clast size and composition. Larger clasts
consist of a variety of compositions. Palaeokarstic
surfaces are also present as shown in figure 15,
solution channels have been caused by acidic rain
eroding the micritic mud.
Figure 15 (right): the top bed of the conglomerate unit.
Note the textural immaturity as well as palaeokarstic
surface. (A4 mapping board for scale)
0
2
4
6
8
10
12
14
16
<10mm 10-50mm 50-100mm >100mm
Figure 16: Histogram demonstrating the clast size within the top bed of the conglomerate.
GR(163950, 819300)

24. 20
Figure 17: A sedimentary log for the ANC unit. A key for the symbols can be found on the loose material.

25. 21
2.3.2 Interpretations
The graded features of the conglomerate beds indicates that this unit was laid down in a fluvial
environment. Graded features demonstrate a current that has slowed down over time to drop the
heavier load first and the smaller pebbles.
A fluvial environment can also be supported through the lack of marine and terrestrial fauna fossils
present. The presence of sandstone matrix as well as clasts from much older units can be attributed to
the penecomptemperaneous erosion, entrainment and transporting of lithic fragments through the
means of fluvial action. Lack of other sedimentary structures such as cross stratification also shows the
current was not very strong, potentially forming as part of a lacustrine environment fed by rivers. The
river system was flowing on a trend of generally NW-SE as the pebbles have been imbricated in such
a way that they are orientated as such.
Figure 18: Above is a rose diagram to show the trend of the clasts within the An Coire
conglomerate taken over multiple beds.

26. 22
2.4 Allt Tarsuinn Limestone Formation
Next in the sequence of sedimentary rocks is the Allt Tarsuinn Limetone. This limestone unit onlaps
onto the conglomerate with a conformable boundary and outcrops in a similar fashion. Exposure of the
limestone is much more significant than the conglomerate but still continues in a linear fashion from
the very North of the mapping area (around Harrapool) to the most Southern point of the area around
Loch an Eilein. The outcrop pattern of the limestone is not consistent around the centre of the mapping
area as there is evidence that the bedding surfaces have been displaced by faulting in some way.
Usefully, inferred contacts are much easier to trace with this unit as the top of the bed is host to a
number of palaeokarstic surfaces such as sinkholes that only occurred within limestone units.
Vegetation is also a factor as there are more lush green ferns growing on the rock and therefore the
unit can be traced to some degree of accuracy. Exposure of the limestone is generally poor but the best
exposure can be found around river systems such as Allt a’Choire.
2.4.1 Observations
The base of the Allt Tarsuinn Limestone occurs in north of the mapping area. Interbedded units are
present at the very base as the limestone is interbedded with fine dark mud layers that are
approximately 10cm thick as well as sandy beds that contain texturally mature medium grained
sandstone that is slightly thicker with an average thickness of 30cm. Both mud and grains are present
throughout the whole stratigraphic sequence, this means that the Allt Tarsuinn Limestone is
Allochtonous. At the base of the limestone, there is greater grain support as most of the beds consist of
wackestones and packestone with a transition into a more micritic composition as the presence of
calcite spars diminishes.
Figure 19: Limestone beds of the lower Allt Tarsuinn unit. Note the clear interbedded mud
layers on the right hand side of the photo.

27. 23
Rivers provided excellent localities for exposure in an area where coastline was not available to
provide clean access to rock surfaces. Allt a’Choire is such a river. Allt a’Choire demonstrates that as
the limestone progresses upwards stratigraphically, there is less grain support therefore results in a
much more mud supported rock. Micritic beds in this sequence are generally thinner and contain a
complete lack of fossil life.
Interbedding becomes the primary feature once again as the top of the limestone is reached. Fine to
medium grained sandstones have been deposited in thin beds between the existing micritic limestone.
Sedimentary structures are present almost exclusively in the sandy beds with evidence of cross-sets,
laminae as well as ripples marks topping one of the beds.
The sandstone interbeds continue to the very top of the limestone unit to finish the sequence.
Figure x: Locality showing the lowest stratigraphic beds of the limestone.
Figure 20: Allt a’Choire has eroded the river sides in such a way as to exposure the unit. This
image clearly shows the interbedded limestone and sandstone at the top of the unit.

28. 24
Fossil content is relatively exemplary in the Allt Tarsuinn Limestone. Beds containing mostly sparite
at the base of the unit (around the An Coire locality).
Beds of the limestone contain an abundance of fossils such as bivavles, gastropods and cephalopods.
Many of these are concentrated into only a single bed.
Gastropods (Cerithioidea)
The first fossil that really stood out within
the unit is a gastropod fossil that seems to
be remarkably intact considering the
states that some of the other fossils are in.
Figure x on the right clearly shows a cross
section through the whorl inside the shell
of the animal. Although this specimen is
upside down, the aperture of the shell can
be seen to be facing towards the camera.
This way, a dextral shell is to be assumed.
Descriptions of this gastropod shell as
well as many gastropods fossils in the
surrounding beds lead to the conclusion
that this particular specimen is part of the
Cerithioidea superfamily. Lias beds of
Jurassic age commonly contain this
gastropod. Preservation is not sufficient
enough to allow a species or genus
specific diagnosis though. Most gastropod
fossils are found intact in the Allt
Tarsuinn Limestone with only a select
handful demonstrating any evidence of
post-death breakup.
Figure 21: Cerithioidea within the ATL unit.

29. 25
Cephalapods (Franziceras sorleyi)
Cephalapod fossils are also common in the
limestone. Identifying cephalopods fossils is
much easier due to their distinctive shell shape
and features despite the small size of most of the
specimens. All of the whorls have been exposed
on this specimen quite clearly with distinct ribs
that are also present around the entirety of the
coiled shell. Distinctive features such as these
used in conjunction with prior knowledge of Lias
beds of the early Jurassic, this allows an
identification that this ammonite is Franziceras
sorleyi. Examples of this fossil can be found
nearby on the Isle of Raasay too (Morton 1999).
It is no surprised to find ammonites and
gastropods together. They commonly co-exist in
the same marine fauna.
Figure 22 (right): Franziceras
sorleyi present in the Allt Tarsuinn
Limestone beds that are
photographed in figure x.

30. 26
Other miscellaneous fossils features exist in the limestone beds. Fossils are present in a clear death
assemblage with only a select few remaining intact. Such breakup of fossils is clearly indicative of a
powerful high energy event or post-deposition breakup through the action of wave energy. Specimens
are seen to have completely destroyed shells, some fossils such as bivalves have managed to retain
their shape albeit in a disarticulated form, leaving only one valve behind.
Figures 23 and 24 (above): Two
photos that show the clear breakup
and disarticulation of the fossils in
the limestone.

31. 27
2.4.2 Interpretations
All of the evidence points towards the Allt Tarsuinn Limestone having been deposited in a marine
environment. Most of the lower beds contain intact fossils that have not been destroyed or
disarticulated in any way. An environment that provides good deposition would not have a powerful
current and be relatively sheltered. A tidal lagoon would be a good explanation, providing shelter for
the fossils as well as a fresh supply of both food and oxygen. In the beds further up in the sequence,
evidence of post-depositional break up through wave action or a death assemblage through a storm
event seems a likely hypothesis for any potential high energy events. These events would be periodic
in nature. Presence of sandstones in the upper sequence suggests a more terrigenous input with the
possibility of a more deltaic/ tidal flat environment beginning to take shape, fitting in with the general
progression of the Jurassic beds as the Druim Bhain Sandstone is deposited.

32. 28
Figure 25: A sedimentary log for the ATL unit. A key for the symbols can be found on the loose material.

33. 29
2.5 Druim Bhain Sandstone Formation
The Druim Bhain Sandstone (DBS) makes up the majority of the mapping area in terms of land area.
Contact between the Druim Bhain Sandstone and the Allt Tarsuinn Limestone is clearly visible at the
road side on the Druim Bhain road itself. Exposure of the Druim Bhain Sandstone is very poor, only a
select number of localities actually have any rock surface that can be worked with. Roadside exposure
provides the best look into this unit, giving a cross section through the bedding of most of the unit.
Exposure of the unit is ended by the road, any further and drift covers the unit entirely.
2.5.1 Observations
The DBS is made of sandstone mudstone interbeds that have roughly the same thickness throughout.
Beds in the DBS are on average 30cm in thickness and make up the entirety of the unit. Sandy beds
are made up of fine to medium sized sand that are well sorted as well as sub rounded. Overall the
colour is generally brown/ grey on the weathered surface with a slightly pinker tinge on the
unweathered surfaces. Mudstone beds are found in conjunction with the sandy beds, such beds are
noticeably darker in colour with a very fine grain size as well as being well sorted and well rounded.
Differentiating the mudstone from shale is simple as the beds of mudstone in the DBS are competent
and will not break with a low amount of force applied.
Sedimentary structures are present throughout this interbedded sequence. Commonly, cross
stratification is present mostly within the sandy beds of any exposure. As is to be expected with sand
and mud, load casts are present as the more dense sand sinks into the less dense mud below it.
Sedimentary structures are not extensively present, only occurring a few times in around 5m of
bedding.
Figure 26: An outcrop of the Druim Bhain Sandstone with a clear thick mud layer in
the middle of the outcrop.

34. 30
The thick mud layer in figure 26 is host to a large number of fossils. Fossil life is abundant in this
layer and this layer only. No other fossil life has been found within the other beds on the exposed rock
face at the side of Druim Bhain.
Gryphaea
There is only one type of fossil present in the mud layer,
this fossil is distinct in nature and quite easy to identify
due to the distinctive shape. Fossilised shells of the
organism have an atypical bivalve shape that makes
identification quite easy. One large curved shell is
encompassing the smaller shell in a distinctive ‘curled
toe’ fashion. This one feature allows me to identify the
shells found in the Druim Bhain Sandstone as Gryphaea.
Palaeocurrent direction can be ascertained simply by
observed the alignment of Gryphaea as preservation has
been sufficient enough to allow for this. In the case of the
Gryphaea contained within these mudstone beds, the
palaeocurrent was moving in easterly fashion (as in
flowing towards the west).
Figures 27 and 28: The image on the right shows
singular valve Gryphaea within the mud layer of
the DBS. The image below is a sketch of how this
relates to current direction. (From Coe, A. L.
(2010)
W E

35. 31
Figure 29: A rose diagram to show the overall orientations of the Gryphaea within the
Druim Bhain Sandstone unit.

36. 32
2.5.2 Interpretations
The Druim Bhain Sandstone is part of a deltaic system. Interbeds of sand and mud as well as
corresponding sedimentary structures provide ample evidence for an environment in which there has
been a persistent fluctuation in sea level to produce both sand and mud layers. The change in sea level
results in sediment originating from different sources, hence the interbedded unit. Mud layers
correspond to more organic rich deposits. As part of a generally transgressive system, the Druim
Bhain Sandstone continues the trend left from the top of the Altt Tarsuinn unit. The Heaste Shale
(discussed in the next section) also continues this trend.
Figure 30: A triangle classification system for a delta with the potential position of the Druim Bhain
Sandstone. This triangle has been edited from (Vakarelov and Ainsworth 2013) which itself has been
edited from (Massey, Fernie et al. 2013)

37. 33
Figure 31: A sedimentary log for the DBS unit. A key for the symbols can be found on the loose material.

38. 34
2.6 Heaste Shale Formation
The Heaste Shale Unit is the youngest unit within my mapping area. Primarily, the unit outcrops on a
small scale in the South-Eastern region of my mapping area, mostly around the Druim Bhain road.
Exposure of the shale is generally good considering the small scale of the unit itself. Mostly being
visible around areas of erosion or other activity, an example of this is the Allt A’Chnoic Charraich
River creating a cutting where the shale is visible. Another example is the road itself with human
activity exposing the unit through excavation.
2.6.1 Observations
The Heaste Shale (HS) unit is bedded in nature with a distinct dark grey/ black colour that is visible
easily. Shale is fissile by nature and the Heaste Shale is no different, rock is easily torn away from the
face and consequently there is abundant debris left over at the base of any exposure. Grain size is
incredibly small at much less than 150μm, this is to be expected from a mud rock. Fissility
distinguishes this unit from a mudstone unit, mudstone is competent and would not break up on
contact.
Non-clay minerals are found within the rock. Primarily, the main mineral found is white in colour with
a light brown tinge, has a pearly lustre and only a hardness of 3. Flakes of this mineral glisten in the
sunlight due to the perfect cleavage. After deducing the characteristics of this mineral, the conclusion
is that the mineral is muscovite mica.
Figure 32a: A photo of a waterfall on the Allt A’Chnoic Charraich River directly south of Loch an Starsaich. Notice
the highlighted shale beds. (GR164650,818300)

39. 35
Shale beds located particularly at the side of the Druim Bhain road north of Heaste are abundant in
fossil remains. The fissile nature of the shale beds allows the fossils to be picked out easily with very
little rock residue remaining on the specimens themselves. Like the DBS unit in the earlier section, the
fossils located within the shale are Gryphaea. A common fossil found in colonies across the British
Isles. Gryphaea is easily identified in this case because of larger ‘toenail shaped’ valve. Hence the
‘Devil’s toenail’ nickname.
Figure 33: Photo of the Gryphaea fossils located within the Heaste Shale Formation. Highlighted with black outline
Figure 32b: Muscovite Mica flakes are clearly visible as shiny specks in the Shale

40. 36
2.6.2 Interpretations
Heaste Shale is the final bed of the Jurassic sequence of beds after the Bheinn Shuardail Limestone. A
general trend can be picked out as a transgressive land system with an overall drop in sea level. The
Heaste Shale represents the last stage of this event. Presence of muscovite mica indicates there is a
nearby terrigenous source of sediment so the depositional environment must have easy access to fresh
sediment from the land. Orientation of Gryphaea fossils as well as their articulated nature points
towards an offshore marine setting containing areas such as sand bars and lagoons with the occasional
fluvial input.
Figure 34: Another rose diagram containing information for the orientation of Gryphaea.
Notice the palaeocurrent direction has not changed much from the Druim Bhain Sandstone.

41. 37
Chapter 3 – Metamorphic activity around Bheinn Shuardail
The intrusion of the large granite pluton has caused a wide variety of effects in the proximity of the
body itself. Interactions with the country rock and elements within the country rock have produced a
numbers of features that have been observed and noted down. Primary observations for this section
will be the products of contact metamorphism within the Bheinn Shuardail Limestone leading up to
the Kilchrist Granite contact. Secondarily, the chapter will cover mineralisation that has occurred
around the granite due to hydrothermal activity.
3.1 The effects of contact metamorphism on the Bheinn Shuardail Limestone caused by the intrusion
of the Kilchrist Granite
The metamorphism varies across the BSL unit. I observed three distinct zones in the field where the
dolomitic limestone moves through three mineral assemblages as the localities are located closer to the
granite contact. In the coming pages, observations that were made in the field will be outlined and then
the theory behind their origin.
Figure 35: The above map shows the rough extent (exact position made impossible due to
limited exposure) of metamorphic zones within the BSL.

42. 38
3.1.1 Zone 1
Zone 1 is the first zone in which contact metamorphism has
been noticed. The chert nodules have begun to show signs of
alteration into different minerals in this zone. That begins
approximately 750m away from the granite contact. Figure
36 on the right shows the mineralogical change in regards to
the chert nodules present in the limestone. The mineral on
the outside of this nodule was white, incredibly soft (easily
scratched by my fingernail) and has a pearly lustre, leading
to the belief that this mineral is Talc. There are some
nodules that have remained unaltered within this zone
towards the boundary with the unaltered zone on the Eastern
section of Bheinn Shuardail.
3.1.2 Zone 2
Zone 2 begins to show greater evidence of contact metamorphism towards the granite contact as a
result of greater exposure to the heat of the intruding magma. The chert nodules have begun to
disappear at this stage as the SiO2 is consumed first within the reactions, this is because the reaction is
isobarically invariant (Winter 2014) further detail on reaction will be given in section 3.1.4.
Further metamorphism has resulted in the production of a new mineral. Presence of this new mineral
is a lot more widespread across the surface the limestone. The new mineral was exhibits a higher
hardness (5 or 6) with a white colour and a silky lustre. This mineral was identified as tremolite. The
presence of tremolite is the result of further metamorphic reaction brought about by the increase in
heat available towards the pluton.
Figure 36: Talc formation on chert
nodules in zone 1

43. 39
Figure 37: Tremolite formation in the dolomitic limestone. Chert nodules have mostly
disappeared at this point.

44. 40
3.1.3 Zone 3
Zone 3 is the zone where metamorphism is
the most prevalent. This zone is the most
distinct and this is clearly evident just by
sight. Zone 3 exists from approximately
200m from the granite contact and finishes
at the body itself.
The mineralisation in this zone is
widespread, the rock has been changed
extensively in comparison to the unaltered
zone. The weathered surface of the rock face
is still the grey colour of the rest of the unit
but any fresh face reveals bright white
crystals of calcite. These calcite crystals are
relatively soft (3 hardness) and can be
broken apart easily. Limestone in this zone
has effectively become marble at this point.
Alongside the calcite crystals, there is an
abundance of tremolite across the zone.
Zone 3 is distinguished by the growth of a
new mineral. This mineral has a green/ lime
green colour with a vitreous lustre, this
mineral also has a much higher hardness
than the surrounding rock (6 or 7 hardness).
This mineral is forsterite. Forsterite is one of
the higher grade minerals in the sequence and symbolises the most heat altering the rock unit.
The forsterite growth ranges from a small amount of mineralisation on a small scale typically only a
few centimetres across all the way up to mineralisation on a larger scale. This can be seen on the larger
rock faces, giving the rock face a green tint.
Figure 38: Example of forsterite mineral growth

45. 41
Figure39:Forsteritemineralgrowthobservedonalargerscale

46. 1
3.1.4 Causes/ Background
As has been mentioned in the previous few sections, the contact metamorphism of the limestone has
been caused by the intrusion of the Kilchrist Granite into the Bheinn Shuardail area. The heat from the
granite has worked in conjunction with the chemistry within the BSL to produce an evident
mineralogical change. There will be more background around the granite in chapter 4 but all the
information that is needed for this section is that the granite has produced heat for subsequent
metamorphism. In this section, there will be an overview of the chemical change as well as a more in-
depth look into the individual zones.
Overview
The specific mineralisation seen in the zones would not have been possible without the siliceous chert
impurities present in the BSL. There is a T-XCO2 phase diagram that has been produced through
experimental data (Winter 2014) and can be used to plot the reaction path observed in the field.
The above table shows the change in composition of the rock over time. This phase diagram represents
an open system, the fluid that helps the reactions along has a constant and replenishing source.
Examples of which would be a marine or meteoric source percolating through the rock. This keeps the
fluid composition constant so the reaction path shown in figure 40 is represented by a vertical path up
Figure 40: T-XCO2 phase diagram showing the changing mineral assemblages of siliceous
dolostones with changing Temperature and ratio of CO2 at constant pressure. The red arrow
shows the reaction path from observations in the field. (Winter 2014)

47. 2
the diagram. The specific location of the arrow is controlled by the ratio of CO2 and the mineral
assemblages observed in the field match up with the triangles present on the phase diagram. The grade
of metamorphism is affected by the size and composition of the igneous body as well the convective
ability of the hydrothermal fluids.
Zone 1
Zone 1 was shown to contain the talc
that has been produced at the lowest
level of contact metamorphism. This
reaction usually occurs whether in a
system open to fresh external fluids or
a closed system. Closed systems
usually occur at greater depths where
the rock is more compacted, therefore
less porous and permeable. On the
right a triangular compatibility shows
the composition of the BSL within
zone 1. Below this paragraph is a
reaction demonstrating the mineralogical
change within this zone, silica is consumed
first and then the temperature rises again for the second reaction as the granite is approached.
3Dol + 4Qtz + H
2
O = Tlc + 3Cal + 3CO
2
Figure 41: A triangular compatibility diagram showing the
mineral assemblage in zone 1. Source: Winter 2014

48. 3
Zone 2
Zone 2 shows the continuing
reaction path into the
Tremolite zone. Silica has
been consumed in a previous
reaction so the production of
Tremolite can be
demonstrated in the below
reaction and as a result the
chert nodules/beds are no
longer present and the
Tremolite has grown
extensively across in the rock.
Zone 3
Zone 3 is the third and final zone
present all the way up to the
granite contact that results in the
production of forsterite. Forsterite
is produced has been produced due
to the relatively low level of
siliceous impurities and the low
ratio of CO2. The reaction for this
is shown below.
Figure 42: A triangular compatibility diagram showing the
mineral assemblage in zone 2. Note the Tr in tie line Source:
Winter 2014
2 Tlc + 3Cal = Tr + Dol + CO
2
+ H
2
O
11Dol + 8Tr = 8Fo + 13 Cal + 9CO
2
+ H
2
O
Figure 43: A triangular compatibility diagram showing the
mineral assemblage in zone 3. Source: Winter 2014

49. 4
Skarns
Upon further search around Bheinn Shuardail, there were other geological features around the granite
that presented themselves. The specimens seen in the photos are found at the base of Bheinn
Shuardail, within zone 3 and very close to the granite contact. This section will outline the
observations made in regards to specimens and the small area in which they were found.
The first specimen shown is a piece of country rock (basalt) with evident mineral growth. The blue
mineral was relatively soft with a hardness of 4, had a dull lustre and was opaque. Any cleavage was
unable to be identified due to the tiny nature of the crystals. Identification of this mineral was deemed
to be azurite. Evidence of another mineral growing next to the azurite is present with green crystals
surrounding the blue. Another specimen shows much more growth of this green mineral. Green
colour, 4 hardness, dull lustre as well as no discernible cleavage and an opaque nature. These
characteristics indicate that this mineral is malachite, found so often next to azurite.
Skarn material originates from metasomatism of
the surrounding rock as hydrothermal fluids
heated up from the adjacent granite pluton.
Metals in the granite melt are expelled in the late
stages of cooling and become dissolved in the
fluids. This is called a magmatic skarn. Skarn
formation through the alteration of country rock
are called exoskarns and show a sharp contrast in
composition to both the granite body as well as
the rest of the surrounding country rock. Skarns
are commonly associated with S-type Granite
bodies.
Figures 44 and 45: The above image shows the clear
green mineralisation that has occurred. Conversely,
the image on the left shows a specimen of skarn
material containing azurite. Commonly, malachite is
found directly alongside azurite as they are
pseudomorphs of one another. This relationship is
seen on the left image.

50. 5
Chapter 4 - Igneous Features
Skye shows extensive evidence of previous igneous activity and the area around Bheinn Shuardail is
no different. There are several different igneous rock types present that vary compositionally as well
as structurally. Exposure of the lithologies varies in quality depending on factors such as vegetation,
topography and human activity. Some impact of weathering can be seen on the minerals within some
of the rocks. Data such as mineral compositions, trend of the intrusions and other miscellaneous
observations will be included within this chapter alongside interpretations into the origin and
background of past activity.
4.1 Kilchrist Granite
The Kilchrist Granite is the largest igneous body present in the mapping area and has had the greatest
effect on the country rock. The Kilchrist Granite (first described as the Bheinn An Dubhaich Granite
(Harker and Clough 1904) intrudes primarily into the dolomitic limestone that makes up the vast
majority of Bheinn Shuardail., the contact with the limestone is not consistent with the granite
outcropping at seemingly random places around the area of the contact. Exposure of the granite is poor
with the majority of it obscured within the area. Human activity has helped make the granite exposure
better in the form of quarries sections.
Figure 46: The Exposure of the Kilchrist Granite within the Kilchrist Quarry
(GR161950,820150)

51. 6
4.1.1 Composition
Of the exposure of granite found, 4 separate samples were taken to analyse the mineralogy as well as
other analyses about grain size, shape and texture. Compositionally, the granite remains mostly the
same throughout the different localities. Mineral composition is consistent with the felsic nature one
would expect from a granite. Sub-hedral transparent quartz makes up the majority of the granite
samples ranging from 40% to 60% quartz. White/ grey plagioclase feldspars are sub-hedral in the
samples and make up 20% mostly with one sample having only 10% plagioclase. Orange alkali
feldspars are larger and euhedral within the granite and make up 20% of the composition most of the
time. Finally, biotite makes up the lowest percentage of composition, generally 10-20%. Some biotite
grains are much coarser than the rest of the minerals in some samples. Below is a QAP triangle to
show how the composition of the granite changes in the different samples. Sample 1 has been taken
the deepest into the granite body. Subsequent samples were taken in a linear fashion, gradually
moving further away from the main pluton and further towards Bheinn Shuardail. Notice how the
composition changes to a more quartz rich granite as samples are taken further from the main body.
Figure 47: A QAP diagram showing the composition of the granite change at different
localities.
+

52. 7
4.1.2 Origin of the Granite
The Bheinn au Dubhaich granite is an S-type granite that has intruded through the calcareous rocks in
the crust. Crust surrounding the granite intrusion must have been saturated in fluid to allow for the
metamorphic features discussed in the previous chapter to have formed (Emeleus, Bell et al. 2005).
Steep sided contacts with the country rock indicate that the granite intruded more or less vertically
upwards and became significantly more felsic along the way through contamination of the mafic melt.
Bheinn an Dubhaich must have intruded after or caused any folding or faulting events occurred as the
granite itself does not show any signs of deformation induced through folding.
It is possible that the granite intruded into the crust at a similar time to the smaller dykes and sills in
the mapping area as part of a much larger igneous suite responsible for the majority of past igneous
activity in the area. Major periods of igneous activity have occurred in the past with the most recent
occurring in the Tertiary period. The British Tertiary Volcanic province has localities all over the
British Isles from South Wales all the way up to the Scottish Highlands. Bheinn an Dubhaich was part
of a number of plutons intruding up through the crust at the time as fractional crystallisation caused
the composition to differ from the usual mafic dykes and sills that are seen so commonly.
Figure 48: Table of mean grain size of the constituent minerals as well as the mean modal
abundances plotted on figure 47

53. 8
4.2 Smaller scale intrusions
Bheinn Shuardail and the surrouding area is host to a great number of small scale intrusions.
Numerous observations were taken from a number of different outcrops. Most the of the dykes and
sills were trending NW-SE with very few deviating from the overall trend. The vast majority of such
small scale intrusions were basaltic in nature. Very fine crystals (~1mm) as part of an equigranular
texture contributed towards this conclusion as well as the petrology itself as the basalts consisted
primarily of mafic minerals such as pyroxenes, olivine and amphiboles. Some small dykes have cross
cut each other, there is an example of this on the Allt Tarsuinn river bed at (GR164300,819450). At
this locality, a small mafic dyke has become cross-cut by a much larger felsic dyke.
A dyke on the southern face of Bheinn Shuardail stands out amongst the rest. This dyke has large
amygdales present at the top of the dyke near the contact with the limestone. Mineralisation has
occurred and plagioclase has infilled the vesicles left behind after cooling. The phenocrysts of
plagioclase are subhedral in nature and measure between 5 and 10mm in thickness. Basalt dykes
across the area have been subject to weathering and red staining is common. Once again, a heavy
indication of the nature of the iron-bearing minerals within.
Figure 49: A hand specimen of the amygdoloidal basalt found on the southern face of Bheinn
Shuardail.

54. 9
A major outcrop in the south-east of the map is the rhyolite that is exposed around Loch an Starsaich.
This rock unit contains felsic minerals such quartz, feldspars and biotite with a fine grained (~1mm)
mostly equigranular texture although some slightly larger subhedral biotite crystals are present too.
White minerals make up the majority of the Rhyolite (~75-80%) as the orthoclase and biotite make up
the rest of the composition. This gives the rock a much lighter colour overall in comparison to the
much darker basalt intrusions. Rhyolite is much more resistant to weathering than the surrounding
sandstone and consequently dominates the topography.
Figure 50: Above is a triangle for the classification of volcanic rocks. The
composition of the rhyolite and the basalt dykes have been plotted (calculated from
modal abundances). Triangle source: IUGS

55. 10
4.2.1 Emplacement of small scale intrusions
Small scale intrusions in this area are of a similar
age to the Bheinn an Dubhaich granite having
intruded as part of a similar magmatic episode.
Fractures in the rock from either previous or
simultaneous tectonics have produced fractures
that have been exploited by the upwelling magma.
Basalt dykes have not undergone much chemical
change through contamination unlike the rhyolitic
counterpart.
Clearly the amygdoloidal basalt has formed
through the infilling of vesicles where gas has
escaped during eruption either on the surface or
just below the surface as the lava has formed a
skin akin to pāhoehoe seen at other eruption sites.
Figure 51: An example of a small scale dyke
intrusion on Bheinn Shuardail.

56. 11
Chapter 5 – Structural Features
5.1 The Bheinn Shuardail Antiform
The Bheinn Shuardail anticline is clearly present on review of the orientation data. The fold is present
throughout the whole structure of Bheinn Shuardail. With the nature of the orientation data, it is
assumed that the structure is a large antiform that has a slight trend to the NNE. The fold axis is not a
linear straight line across Bheinn Shuardail and the fold itself is an open fold that is ever so slightly
inclined to plunge to the NNE.
Folding could have been caused by the intrusion of the Bheinn an Dubhaich granite. Such a large
magmatic force intruding up into the crust would have uplifted and pushed over any lithologies
present. This is not the case however, the granite does match up with the trend of the fold axis but no
other igneous features around Bheinn Shuardail show any signs of deformation. Older and smaller
intrusions would also have been affected. A likely origin for both the Bheinn Shuardail antiform as
well as the Druim Bhain synform is a past compressive tectonic regime originating from the north-
west and the south-east to produce folds that are trending generally NE-SW.
Figure 52: A stereographic projection of bed orientations for the
Bheinn Shuardail antiform.

57. 12
5.2 The Druim Bhain Synform
The Druim Bhain synform is a very similar fold to the Bheinn Shuardail antiform, possibly caused by
the same tectonic regimes that caused the adjacent fold. Beds outcrop in a typical synform fashion as
the younger units are in the middle of the fold as the older units radiate outwards.
5.3 Other structural features
Minor small scale faulting is present in the central portion of the mapping area. Faulting has disrupted
the outcrop pattern of most notably the Allt Tarsuinn Limestone as well as the An Coire
Conglomerate.
Figure 53: A stereographic projection of bed orientations for the
Druim Bhain synform (poles to planes).

58. 13
Chapter 6 – Geological History (Conclusion)
The area around Bheinn Shuardail is rich in geology. Rock units range from pre-cambrian to tertiary in
age and make for some impressive observations.
At first, there was the fluvial system that led to the deposition of the Cnoc na Cubhaige sandstone
beds. The CCS unit is thrust on top of the younger Bheinn Shuardail Limestone. This limestone was
deposited in a marine environment and subsequently underwent chemical changes through
dolomisation as well the formation of chert nodules and bands.
A hiatus in deposition eventually led to the formation of the An Coire conglomerate unit. This unit has
come about once again in a fluvial system with penecomtemperaneous erosion of the lower
(stratigraphically) units. A wide variety of compositions present within clasts of the conglomerate
support this. During the Jurassic period, the Allt Tarsuinn limestone has onlapped onto the An Coire
Conglomerate as the palaeoenvironment has begun to become dominated by marine successions
evidenced by the presence of Cerithioidea and Franziceras sorleyi. A transgressional system began to
form as the environment began to become more deltaic as the British Isles moved higher in latitude
away from the equator during the late Jurassic period. Deltaic systems controlled much of the
subsequent deposition from this point onwards. Interbedded mudstones and sandstones are indicative
of such an environment as well as the presence of Gryphaea fossils. The final unit to be deposited is
the Heaste Shale unit that represents the final deltaic system.
Periods of deformation have occurred as there are two folds in the area that have affected all of the
geological units in the area. This folding could have been caused by the intrusion of the large granite
body but this is doubtful.
Igneous activity was prevalent in the Tertiary period as the British Isles were subject to extensive
volcanism. The mapping area shows this with the inclusion of large granite pluton as well as a plethora
of smaller intrusions. Heat from the granite pluton in conjunction with a crust saturated with fluids has
also produced remarkable contact metamorphic features.
Side note – Limitations
The topography was the main limitation when trying to study the area. Getting around the mapping
area was difficult and not much can be done to rectify this. Exposure also hampered fieldwork
somewhat, maybe better research using software such as Google Earth would have allowed a better
plan of action to be taken as to where to go during fieldwork and not waste significant amounts of
time.

59. 14
Chapter 7 – References
Coe, AL 2010, Geological Field Techniques, [Electronic Book], Page 89, n.p.: University of
Liverpool Catalogue
Emeleus, C. H., et al. (2005). The Palaeogene volcanic districts of Scotland, Nottingham: British
Geological Survey, 2005 4th
ed.
Hairuo, Q. and E. Mountjoy (1992). “Large-scale fluid flow in the Middle Devonian Presqu’ile
barrier, Western Canada sedimentary basin.” Geology 20(10): 903-906
Harker, A. (1891) “The sequence of the Tertiary Igneous Rocks of Skye.” Geological Magazine 8(11):
506
Harker, A and C. T. Clough (1904). The tertiary igneous rocks of Skye, Glasgow: H.M.S.O, 1904
Issen, K. A. and J. W. Rudnicki (2001). “Theory of compaction bands in porous rocks.” Physics and
Chemistry of the Earth. Part A: Solid Earth and Geodesy 26(1-2): 95-100
Machel, H. G. (2004). “Concepts and models of dolomitization; a critical reappraisal.” Geological
Society Special Publications 235: 7-63
Massey, T. A., et al. (2013). “Detailed mapping, three-dimensional modelling and upscaling of a
mixed-influence delta system, Mitchell River delta, Gulf of Carpentaria, Australia”. Special
Publication – Geological Society of London 387(1): 135-151.
Morton, N 1999, ‘Middle Hettangian (Lower Jurassic) ammonites from Isle of Raasay, Inner
Hebrides, and correlation of the Hettangian-lowermost Sinemurian Breakish Formation in the Skye
area, NW Scotland’, Scottish Journal of Geology, 35, Part 2, pp. 119-130
Nichols, G. (2009). Sedimentology and stratigraphy. [electronic book]. Chichester: Wiley-Blackwell
2009 2nd
ed.
Rasmussen, B., et al. (2013). “Iron silicate microgranules as precursor sediments to 2.5-billion-year-
old banded iron formations.” Geology [Boulder] 41(4): 435-438
Tucker, M, Wright, V, & Dickson, J 1990, Carbonate Sedimentology Chapter 8, pp. 365-400
Vakarelov, B. K. and R. B. Ainsworth (2013). “A hierarchical approach to architectural classification
in marginal-marine systems; bridging the gap between sedimentology and sequence stratigraphy.”
AAPG Bulletin 97(7): 1121-1161.
Winter, J. D. (2014). Principles of igneous and metamorphic petrology, Harlow: Pearson, 2014. 2nd
ed.
Pearson new international edition