Glaciation

Question 1

What are the two types of glacial till?

Answer 1

Basal Till, Ablation

Question 2

Characteristics of Basal Till?

Answer 2

• Deposited as base of glacier melts
• non-sorted and massive (not bedded)
• denser and stronger than any other surficial material
• often finer materials than ablation tills
• low-permeability, cohesive, overcompacted

Question 3

Characteristics of Ablation Till?

Answer 3

• non-sorted and massive (not bedded)
• coarser than basal till with more angular bits
• high bearing strength but less cohesion
• higher porosity and permeability
• can be similar to materials in kames

Question 4

What are the 2 types of glaciers?

Answer 4

Continental and Alpine glaciers

Question 5

What are some indications that an area was glaciated?

Answer 5

1) Erratics
2) Unsorted material
3) Striations
4) Polished Bedrock

Question 6

What is Drift and what is it composed of?

Answer 6

Drift is any material of glacial origin. Composed of:

1) Till - Unsorted unstratified material
2) Outwash - Streams lakes, sorted/stratified.

Question 7

What are some characteristics of outwash deposits?

Answer 7

proglacial outwash deposits (from meltwater leaving glacier)
are similar to post-glacial fluvial deposits (rivers transporting
glacial deposits?)
• found all over in
• outwash deposits can be sorted to not sorted, sand to
boulders, and with tabular stratification
• good bearing strength with relatively high porosity and
permeability
• well-drained unless hight local water table – can be
important aquifers

Question 8

What are some characteristics of glaciolacustrine deposits?

Answer 8

Mostly silt and fine sand, but coarse material near
inflow points
• non-sorted bedding, to laminated bedding
• if lots of sediments = level surface, otherwise shows
pre-existing topography
• when lakes drained, gently sloping terraces remain
• sediments are moderately cohesive, some degree of
plasticity when wet – depends on clay content
• highly erodible
• low permeability in fine silts and clays – may initiate
gullying
• poor bearing strength but may be ok for light structur

Question 9

What are some characteristics of glaciofluvial or glaciomarine deposits?

Answer 9

• From stony, silty clay with little stratification to
laminated silt and clay – mollusk shells are diagnostic
to differentiate from basal till
• fine-grained glaciomarine deposits have slow drainage
• clays/silts containing high water content can liquefy
with seismic shaking, slope failure, or persistent heavy
traffic

Question 10

What’s the material like in Kames and eskers?

Answer 10

Sorted, bedded, less fines, almost no silt and clay, Well drained

Question 11

What landforms do glaciofluvial processes form?

Answer 11

Terraces, raised deltas, large fans, kettles