Fluvial Sediments and Glacial geomorphology

Topographic maps

graphical representation of features on the Earths surfac

Contour line

line connecting points of equal elevation

Eastings

Run vertically, divide map into East and West

Northings

run horizontally, divide map into North and West

Glacier mass balance

= inputs + outputs for given glacier

Inputs

• Regular winter snow

• ad hoc avalanches and wind blown snow

Outputs

• Regular summer melt

• ad hoc from avalancing

Accumulation

Mass inputs

Ablation

mass outputs

Positive mass balance

Accumulation is greater than ablation

• may result in glacier advance

Negative mass balance

Ablation is greater than accumulation

• may result in glacier retreat

Glaciers

Accumulation of snow and ice which flows down under force of gravity

Glaciated valleys

• U shaped

• steep sides

• flat or gentle valley floor

River valleys

• V shaped

• sharp valley floors

• less steep valley sides

Cirques

Circular to elongate bowl-shaped depressions with flat base and steep sides located at headwaters of glaciated valleys

• represent areas of snow accumulation, primary ice source for glaciers

Tarns

Past cirques, often small mountain lakes

Hanging valleys

formed by smaller glaciers feeding larger glaciers, often identified as waterfalls along sides of large glaciated valleys

Horns

Sharp glaciated peaks

Aretes

Sharp ridges that seperated glaciated valleys

Till

poorly sorted sediment directly deposited by ice

Morraines

landforms made of till

Terminal morraines

form at downstream end of glacier adjacent to glacier terminus and typically orientated across valley

Lateral morraines

form at side margins of glaciers and are orientated parrallel with valley

Ground/basal morraine

deposited as discontinuoys sheet at base of glacier