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1. GLACIAL
LANDFORMS
By- Chaitanya Bokre and Aman Singh

2. Key Index
• Introduction
• Major Features Resulting
from Glacial Erosion
o The cirque
o Glacial Troughs
o Hanging Valley
o Aretes and Serrate
Ridges
o Truncated Spurs
o Fjord and piedmont
Lakes
• Depositional Landforms
o Glacial Forms
o Glacial Fluviatile
Forms
o Glacio Lacustrine
Features
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3. INTRODUCTION
Glacier today, except in high latitude and at high altitude , are of minor importance in the present-day shaping of land
form , but those that existed during the Pleistocene left their imprint upon many millions of square mile of the earth's
surface. Many lesser areas were covered by local ice caps. Thousands of valley glaciers existed in mountains where
today there are either no glaciers or only small ones. Some of our finest mountain scenery is to a large degree a product
of glacial geomorphic processes, as are many interesting lowland land forms. In most of the world's high mountains ice
streams have so profoundly modified valley that their forms are distinctly different from those produced by fluvial
erosion. Although the effect of glacial erosion are most strikingly displayed, depositional features are also present and
add distinctiveness to the landscape.
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4. MAJOR FEATURES RESULTING FROM
GLACIAL EROSION

5. The Cirque
• The most common, and probably the most striking, land form in glaciated mountains is the cirque.
• This French term is applied to amphitheater-like basins (the term amphitheater is not strictly correct, for they are not
completely enclosed by walls) which are found most frequently at valley head , but which may not connect in their
distal parts with valleys.
• The widespread distribution of cirques is attested by the many languages which have an equivalent word: the
German kar, the Welsh cwm, the Scotch corrie, and the Scandinavian botn and kjedel. That cirques exhibit many
characteristics is suggested by the many qualifying term which have been given to them.
• They are variously described as simple, compound, hanging, tandem or two- staired, intersecting and nivation
cirques.
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6. • An empty cirque usually display three distinguishable parts,
a headwall, basin, and threshold. Headwall may be a much
a 2000 to 3000 feet high and is steep and free from talus at
its base, even in empty cirque. Scarcity of talus suggests
that there was no role of ordinary weathering processes
but rather that some subglacial process was in operation
which permitted glacier to remove material as rapidly as it
was detached from the headwall.
• The most widely held theory of cirque formation was
proposed by Johnson (1904) . This is generally called the
bergschrund theory because of the importance that he
attached to basal sapping or plucking at the base of the
crevasse, called a bergschrund, which commonly is found
at the head of a valley glacier.
• Objections have arisen to Johnson' theory because cirque
headwalls frequently far exceed in height any observed
bergschrund depth and because many glaciers do not
exhibit bergschrunds.
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7. • A cirque usually shows a definite basining of its floor which extends forward from the headwall and terminates
at a bedrock riser called its threshold. Consequently, cirque basin are commonly sites of small cirque lakes or
tarns as they are called in the British Isles.
• Cirques vary in plan from simple, subcircular outlines to compound ones. Compound cirques represent a more
advanced stage of development and are products of headward cirque extension at varying rates in different
parts of a cirque headwall.
• Cirques are more conspicuous in some regions than in others, even where climatic and topographic conditions
seem to have been equally favorable to the formation of glaciers.
• Conditions that seem to favor maximum cirque development are :
 Rather wide spacing of preglacial valleys so as to permit expansion without intersection of adjacent
cirque at an early stage;
 Snowfall sufficient to form large snowfields and glaciers but not heavy enough to form ice caps;
 Fairly homogeneous rock which permit cirque extension equally well in any direction.
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8. Glacial Troughs
• Next to a cirque, the most distinctive topographic feature in glaciated mountains is the glacial trough. Most glacial
troughs were originally stream-cut valleys, but glaciers usually have a altered them that neither in era s profile nor in
long profile do they resemble greatly stream-carved valleys.
• A glacial trough heads not at a cirque headwall but at the lower edge of a cirque threshold. There is usually a
conspicuous drop from a cirque threshold to the floor of a glacial trough, which has been called a trough headwall.
Trough headwall are likely to be most can conspicuous where more than one cirque contributes ice to a glacial
trough.
• Glacial trough are notably irregular and ungraded in their long profile . Few exhibit the relatively smooth, concave
longitudinal profiles characteristic of stream-cut alleys. Descent of trough floor takes place in a series of glacial reps
or what is sometime called a glacial Stairway.
• In general these steps are more pronounced in the upper than in the lower part of a trough, probably because the
glacier persisted there longer. Each step typically has three component part : a riser, a Riegel, and a tread. A riser
marks the down- all end of each step and the a cent to it from the step below. A riegel is a art of rock bar at the top
of and just back of a riser. A tread is the relatively fiat ft or surface step. It frequently has a reverse up-valley slope
with resulting development upon it of a basin which becomes the site of a rock-basin lake or a chain of lakes, which
because of the similarity of their arrangement to beads on a rosary are called paternoster lakes. 8

9. • The divergences of opinion concerning their origin suggests that
glacial steps are of diverse origin. Although there may be difference
of opinion as to their origin, there is general agreement that they are
expectable features along glacial troughs.
• The cross profile of a glacial trough usually is significantly different
from that of an unglaciated valley in a mountainous area. The
difference is usually described as the difference between a V-
shaped valley and a U-shaped valley. This comparison is not too
appropriate, for not all glacial troughs are U-shaped and not all
stream-formed valleys in the mountains are V-shaped. Probably the
best description of the cross profile of a glacial trough is that it
resembles a catenary curve.
• Differences in cross profiles may be related to such factors as the
thickness of the glacier, the lithology and structure of the rocks in
which the trough is cut and the number of times a valley was
glaciated. Portions of glacial troughs may exhibit remarkably flat
floors. More commonly these flat-floored sections are the result of
deposition subsequent to trough development than of uniform glacial
erosion. They may represent aggraded, postglacial, alluvial floors,
outwash materials deposited accompanying glacial recession, or
lacustrine plains produced by filling of the lakes. 9

10. Hanging Valleys
• In contrast to river valley , which usually have their tributary
valleys joining them accordantly, glacial troughs so commonly
have tributary trough or valley joining the main trough
discordantly that this may be considered normal.
• At one time hanging valley were almost considered prima facie
evidence of glaciation. We understand now that hanging valleys
may be produced in several ways. They may characterize
stream valley , particularly if the tributary streams are
intermittent or much mailer than the mainstream. Tilting of a
region may steepen the gradient and accelerate the downcutting
of a main valley without a corresponding effect upon its
tributaries.
• Faulting may also produce hanging valleys. Usually it is not
difficult to distinguish hanging valleys of non-glacial origin from
those caused by glaciation, because the former is not
associated with a glacial trough. Not all trough junction are
discordant. Glaciers of nearly equal size in tributary valley may 10

11. Aretes or serrate
ridges
• A cirques enlarge by the sapping process mentioned above, preglacial uplands are
gradually consumed by headwall recession. Certainly preglacial up lands exhibit
varying degrees of destruction.
• The somewhat extreme view that cirques are rather static in position and that
sharpening and demolition of peaks takes place through ordinary weathering
processes is not widely held. At an advanced stage of cirque recession, mountain
divides may be nearly consumed.
• All that will be left will be a sharp sawtooth-Iike ridge, which the French have called
an aretes and to which the English term serrate ridge is often applied. An arete or
serrate ridge consists essentially of alternating sags or glacial cols produced by
intersection of opposed cirques and pointed peaks or horns representing
unreduced portions of the original mountain range.
• Well-known examples of horns are the Matterhorn and Weisshorn in the Alps.
Somewhat related in origin to horns but detached from the main mountain range
are monuments or tinds, as they are called in Scandinavia. These are formed
where lateral cirque recession cuts through an upland spur between two glacial
troughs.
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12. Truncated Spurs
• In general, glacial troughs are straighter than unglaciated
valleys. Glacial troughs do conform to the original valley course,
but ice stream may straighten their troughs by abrasion of spur
ends and thereby produce truncated or faceted spurs.
• Different degrees of spur truncation may be seen, varying from
spur ends that have been cut off completely to partially trimmed
spurs till recognizable from rocky knobs or nubbins.
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13. Fjords and piedmont lakes
• Most students of glacial land forms agree that fjords are glacial troughs eroded by ice below sea level, but a few
attribute the great depths of water in them to submergence of troughs formed above sea level.
• Fjords are characteristic features of shore lines in high latitude and are well-developed along the coasts of Norway,
Greenland, British Columbia, Alaska, Chile, and New Zealand. It was once held by some that fjords were largely
tectonic in origin, but that idea has largely disappeared.
• It is possible that the plan of some fjords reflect joint or fault control, but it seems unlikely that many of them were
initially grabens. A feature of a fjord that has evoked considerable speculation in the threshold or sill which is often
found at its terminus. The depth of water here is typically much Iess than farther seaward or head ward in the fjord.
Thus a fjord is really an elongate basin which would become a lake, if sea level were lowered below the top of its
threshold.
• It has been suggested that fjord thresholds are submerged terminal moraine, and in some instances this may b
partly true, but it seem more likely that they result from greater glacial era ion up fjords, where the ice was thick and
actively eroding, and Iess erosion in terminal zones, where the ice was too thin for effective erosion.
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14. DEPOSITIONAL LANDFORMS

15. Glacial Forms
Glacial deposit , in contrast to those of glacially fed streams and glacial lakes,
are marked by heterogeneity of materials and lack of stratification. Three types
of glacial deposits-end moraine, lateral moraine, and ground moraine-may be
distinguished, depending upon whether deposition took place at the end of, at
the side of, or beneath an ice stream.
End Moraines
• The term recessional moraine has been used in the past to designate end
moraines back of the outermost one, the implication being that a series of
end moraines marks successive pauses in the position of a retreating ice
front. Slight oscillations of an ice front as it recedes may result in an
irregular belt of knolls and basins, usually described as knob and basin
topography.
• This type of end moraine is more commonly formed by ice caps than by ice
streams. Not all glaciers build conspicuous end moraines. This depends
upon such factors as whether an ice front maintains it elf in one position
long enough; whether ice-fed streams emerging from glaciers are capable of
removing material as rapidly as it is dumped; and whether the glaciers are
carrying large loads.
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16. Lateral Moraines
• Lateral moraines form along the sides of an ice stream chiefly from
material which are contributed from the valley sides above the glacier
by weathering, snowslides, avalanche, and other type of mass
movement. Two lateral moraine may join to form a medial moraine but a
medial moraine is more of a feature of a glacier surface than a land
form, because it will not persist long after a stream occupies the trough.
• Lateral moraine are frequently patchy and may or may not be present
on both side of a trough for usually portion have been removed by
postglacial stream erosion. Despite this lateral moraines are usually
among the most impressive features found along glacial trough. Small
lake are sometimes found perched above the floor of a glacial trough
between a lateral moraine and the trough wall.
Ground Moraines
• Ground moraine is not nearly so abundantly associated with ice
streams as with ice caps. It is scarce because an ice stream is
particularly effective erosional agent which vigorously abrades and
plucks it bedrock floor. Hence, ground moraine is likely to be at best
thin and patchy in glacial trough . 16

17. Glacial till
The regional result of deposition by ice caps, where complete burial of preglacial topography took place, is a till plain.
An understanding of some of the features that distinguish till plains entails an appreciation of the physical
characteristics of till. One outstanding feature of till is its physical heterogeneity. There is no size assortment and no
evidence of stratification. The bulk of the material usually is of clay, silt, or sand sizes, but pebbles and huge boulder
may be present. Tills high in clay may show a certain amount of lamination or fissility caused by compaction under ice
pressure that may be mistaken for stratification. Alternating layers of slightly different texture and composition may
also give an effect of pseudo- stratification. Lithologic and mineralogic heterogeneity characterize tills , for most tills
were derived from several rock types. Despite this, tills usually do exhibit a certain consistency in lithology which
makes it possible to describe them as clay, sandy, gravelly, or stony tills. Tills lithology is commonly related to local
bedrock, and in most places the greater part of the material comprising till was derived from near-by bedrock and not
from rocks hundreds of miles away. Till in areas of granitoid rocks, as in New England, is characteristically pebbly and
bouldery; till in areas of sandstone is sandy, and till overlying shales, dolomites, and limestones is typically clay till,
although where there are limestones and dolomites much of the material of clay size is pulverized limestone or
dolomite rock flour. Frequently a till section displays two distinctly different types of material, a lower part which is
compact and fine-textured, and an upper part from which most of the clay and silt fractions are lacking. These are
sometimes interpreted as tills of different ages, when actually they are the same age. The compact lower portion is
basal till and is believed to have been deposited largely by lodgment beneath the ice. The less compact and more
permeable material above is called superglacial till or ablation moraine and is thought to have been let down during
final down wasting of the ice. The large amount of water that resulted from down wasting flushed out most of the clay
and silt fractions, leaving a coarse-textured till.
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18. Drumlins
• Strikingly streamlined hills called drumlins are found on some till
plains. Why drumlins are found in some areas and not in others is
not understood. Most drumlins are composed of till, but some have
stratified materials as a surficial coating or lens beneath till.
• A typical drumlin is half ellipsoid in shape like an inverted spoon,
but many variations are found. Double and triple forms may be
found arranged en echelon. Generally, drumlins display a striking
parallelism of arrangement.
• Drumlin vary in height from 20 feet to 200 feet or more and in
length from a fraction of a mile to several miles. They are rarely
found singly but exist in great field or swarms
• Drumlin characteristically lie several miles back of end moraines.
Some consider them to be erosional features, and others attribute
them to glacial deposition.
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19. Much of the material acquired and transported by an ice stream is ultimately got hold of, transported, and finally
deposited by streams flowing on, within, beneath, and beyond the glacier. Depo it of such origin are classed as glacio-
fluviatile. They may retain some of the characteristics of glacial debris, but they show a degree of assortment and
stratification roughly proportional to the distance that they were carried by stream . The most common land form
belonging to this class found in areas of mountain glaciation are valley trains, esker , kame terrace, kame, and
outwash fans or deltas.
Valley Trains
• Valley trains consists of outwash sand and gravel heading usually at an end moraine and extending down-valley
from it. Except for those still in the process of formation, they are likely to be marked by terraces above present
valley floors.
Eskers
• Eskers are sinuous ridges of assorted and somewhat stratified sand and gravel which are believed to represent
filling of superglacial, englacial, or subglacial stream channels. They are far more common in areas of continental
glaciation than in glacial troughs, for eskers are features formed when ice stagnates, and stagnant ice is rare in
valley glaciers.
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Glacio-fluviatile forms

20. Kame Terraces
• Kame terraces may form in glacial trough, but not too commonly. They, along with eskers and kame , belong to a
class known as ice-contact features, so-called because the materials of which they are composed were laid down
against an ice surface. Kame terraces are fillings or partial fillings of depressions between a glacier and the sides
of its trough. These depressions are called losses, and they owe their existence to the more rapid rate of melting
which takes place here because of the added effect of heat absorbed or reflected from the valley sides.
• The term kame was introduced into geologic literature by Jamieson in 1874 and has been applied to so many
different types of glacial and glacio-fluviatile deposits that it has been argued by some that it is so ambiguous that it
should be abandoned.
• It is difficult to define a kame, but almost everyone agrees that it is a mound or hummock composed usually of
poorly assorted water-laid materials. Most of them are probably ice-contact forms whose materials were laid down
in intimate contact with an ice surface, although they may have undergone modification by slumping subsequent to
melting of the ice.
• The term kame complex is a useful one if we restrict it to an assemblage of kame and do not apply it to any area of
sag and swell topography. Kames are sometimes so numerous in end moraines as to cause moraines to be
designated as kame moraines, but even here till is likely to be more abundant than water-laid materials.
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21. 21

22. • Lakes, present or extinct, are common features of glaciated valleys. The more
common types are: rock-basin lakes in cirques and upon the treads of glacial
steps; lakes back of terminal and lateral moraines; lakes formed by the damming
of tributary valleys by a valley train in a main valley; and those in the basins of
knob and basin topography.
• Lakes are ephemeral land forms, and their sites soon become lacustrine plains
by filling with inwash or lowering of their outlets by erosion. The small lacustrine
plain which are often found in glaciated mountain valleys are often striking
because their flatness contrasts sharply with their surroundings.
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Glacio-lacustrine
features

23. THANK YOU
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