Destination: understand how moraine is
transported and deposited to form
Route: examine the different types of
moraine, drumlins, glacial till and
erratics. Identify, describe and explain
Match the feature to the correct description
Glaciers transport large amounts of debris.
The debris may be derived from rockfalls on
the valley sides.
It can be transported on the surface of the
glacier (supraglacial debris).
It can be buried within the ice (englacial)
It may be at the base of the glacier
It will eventually be deposited, mainly by
melting at the snout
Processes of Glacial transport
As well as eroding the rock over which it flows, a valley
glacier is also capable of transporting large amounts of
The lower few metres of a glacier that contain debris
picked up from the bed.
Rhonegletscher, Swiss Alps.
blue ice of
Small parts of the glacier bed are visible
inside an ice cave at the front of Rhone
Glacier, Switzerland. The ice is moving
from left to right.
Glacier bed Bedrock, or debris, over which the glacier flows.
Debris which has been released from ice at the base of a
glacier. Individual stones usually show signs of rounding as
a result of abrasion at the contact between ice and
Taylor Glacier, Victoria Land, Antarctica, showing the formation of subglacial
debris (basal till) that has melted out from the dark striped basal ice layer
Lines or series of mounds of material mainly
running across glacial valleys.
Main type is terminal/end moraine found at
1. Ridge of material (or several mounds) across
2. Elongated at right angles to ice advance
3. Steep-sided, particularly at ice-contact side,
reaching heights of 50-60m
4. Crescent-shaped, moulded to form of snout
5. Formed from unsorted ablation material
6. Formed when ice melts during snout standstill.
Terminal moraine A prominent ridge of glacial debris
formed when a glacier reached its maximum limit during a
A massive terminal moraine marks the greatest
advance of a glacier, during the last centuries, in
Cordillera Huyhuash, Peru. A lake has formed
between the terminal moraine and the glacier front.
As glacier retreats, a series of moraines
forms along valley, marking points where the
retreat halted for some time
If there is climate cooling, previously
deposited moraine may be shunted up into a
mound called a ‘push moraine’
Recessional moraine Ridge of debris representing a
stationary phase during otherwise general retreat.
Recessional moraines deposited in the 1920s by Steigletscher, Bernese Alps,
Switzerland act as a dam for the lake in the centre of the photo.
A complex landform ranging from a few metres to tens of
metres in height comprising assorted debris that has been
pushed up by a glacier during an advance.
Push moraine in front of Thompson Glacier, Axel Heiberg Island, Canadian Arctic.
Different types of moraine
Moraine is a type of landform which develops when
the debris carried by a glacier is deposited.
Lateral moraine Debris deposited along the side of
a glacier, comprising both rockfall debris from above and
debris ground up by ice-marginal processes.
A pair of lateral moraines Vadret da Tschierva, Grisons, Switzerland
Medial moraine Distinct ridge of debris occurring
on the surface of a glacier where two streams of
Medial moraines on a tributary of the Kaskawulsh Glacier, Icefield Ranges,
Material that is directly deposited by the ice
Till – unsorted mixture of rocks, clay and sand
that was mainly transported as supraglacial and
englacial debris and deposited when the ice
Individual stones tend to be angular or sub-
angular, unlike rounded river and beach material
Reflects the character of rocks over which the
ice has passed
E.g. East Anglia till contains granite from
Till A poorly sorted mixture of mud, sand
and gravel-sized material deposited directly
from glacier ice.
Basal till from the last major glaciation in Britain, c. 18,000 years ago;
north shore of Loch Torridon, NW Scotland.
Where have you come across boulder clay
Lodgement till – subglacial material that was
deposited by the actively moving glacier. A
drumlin is a typical feature formed from this
Ablation till – produced at the snout when
the ice melts. Terminal (end) push and
recessional moraines are formed from
The rose diagram shows the orientation
between 0º and 210º of the long axes of
stones obtained from a sample of till. The
table shows some of the remaining
A large block of rock that has been moved
from one area and deposited in another
which has a very different geology
A boulder or large block of bedrock that is being, or has
been, transported away from its source by a glacier
Huge erratics near Bremgarten, Canton Aargau, Switzerland which were
deposited during the last glaciation
A streamlined hillock, commonly elongated
parallel to the former ice flow direction,
composed of glacial debris, and sometimes
having a bedrock core; formed beneath an
actively flowing glacier.
Group of drumlins near Hirzel Pass, Swiss Plateau
From Gaelic word ‘druim’ meaning a rounded hill.
Smooth, oval shaped small hills, often resembling the
top half of an egg
Can be as long as 1.5km (although most are much
smaller) and up to 50m in height
Steep end called stoss
Gently sloping end, lee
Elongated in the direction of ice advance, stoss
upstream and lee downstream
Found in groups known as swarms – ‘basket of eggs
Formed from unsorted till
Found on lowland plains e.g. central lowlands of
Drumlin Field in
York state. The
with glacial flow.
Drumlins form underneath the ice
The ice is overloaded with debris and then
streamlined by ice advance?
Indicative of low flow?
Tell us direction of ice movement
There are different theories of their
1. Sub-glacial deformation
2. Subglacial floods
‘The most popular and featured theory relates to the
glacier being overloaded by moraine in contrast to the
energy it has and so struggles to cope with transporting
such an amount in the lower parts of its course. Thus, the
moraine is deposited. The characteristic elongated shape is
thought to be related to the direction of movement of the
ice with the blunt end facing the oncoming ice and the
tapered end being in the lee of it. Moraine contained within
the drumlin tends to be oriented to reflect this pattern. It
is believed that obstacles (possibly outcrops of resistant
rock – as rock cores have been noted in some drumlins) in
the path of the glacier may be responsible – encouraging
the deposited material to be moulded into the
characteristic elongated shape. This theory of subglacial
deformation is the more written-about alternative. Other
ideas consider the role of glacial meltwater – where this is
seen as being responsible for eroding large hollows beneath
the ice and their subsequent in-filling led to the drumlins.’