Glaciers Landmarks of the Past

Glaciers: Large mass of ice, air, rock debris.Glaciers: Large mass of ice, air, rock debris. –At least partially formed on land –Constantly moving –Permanent Glaciation: Formation, activity, and retreat of glaciersGlaciation: Formation, activity, and retreat of glaciers Firn: Snow that has survived the summer, first step to becoming glacial ice.Firn: Snow that has survived the summer, first step to becoming glacial ice. Pressure compacts snow and makes it into glacial icePressure compacts snow and makes it into glacial ice

Types of glaciers are:Types of glaciers are: –Valley/Alpine: glacier formed from a cirque (bowl shaped depression in a mountain) and spread into a valley

–Piedmont: valley glacier that extends beyond the mountain

–Ice Cap: covers mountain top and spreads radially –Continental/Polar: glacier formed at the poles –Ice sheet: Large sheet of ice that covers earths topography

Glacier Formation Accumulation: adding of materials to glacierAccumulation: adding of materials to glacier Ablation- removing of materials from a glacierAblation- removing of materials from a glacier Equilibrium line: where accumulation zone and ablation zone meetEquilibrium line: where accumulation zone and ablation zone meet

Glacial Drift Glacial Drift: Movement of glacier (easiest path) Pressure: Force that drives glacial movement Ductile: Can be reshaped (ex. silly puddy) Basal Sliding: Sliding of glacier on super cooled water Ice Stream: fast moving part of a glacier ½ mile/yr

Glacial Striations Glacial Striations: Scratches in rocks made by glaciers dragging other smaller rocks over the striated rock

Glacial Deposition Deposition: Dropping of materials by glaciers Glacial Till: Material dropped by glaciers made of: –Rock Flour: Finely ground rock powders –Erratics: Large rocks or boulders carried away from their place of origin

Beautiful turquoise lake near valley glaciers in Alberta, Canada. Meltwater streams carry rock flour into the lake. The color of the lake is caused by all the very fine sediment suspended in the water.

Glacial Erratics

Types of Glacial Depositions Moraines: Depositions left on the outsides of glaciers Types of Morains –Lateral: side of glaciers –Medial: between two glaciers –Terminal: end of glacier

Convergent Ice flow: 2 glaciers meet and flow together as 1Convergent Ice flow: 2 glaciers meet and flow together as 1 Divergent Ice Flow: 1 glacier separates into 2 different glaciersDivergent Ice Flow: 1 glacier separates into 2 different glaciers

Moraines

Glacial Deposition (continued) Kame: Hill or mound of glacial till and ice that broke off of glacier Kettle: Bowl shaped depression found after glacial ice is broken off, covered with till, and compresses the earth. Kettle lake: Kettle that has collapsed filled and with water Pothole lake: Lake that forms at a terminal moraine or by a Kame Drumlin: Sediment filled depressions

Glacial Deposits (continued) Outwash: Water that rushes out from under or above a melting glacier Esker Braided Stream Delta: Deposition of sediment at mouth of a stream

Esker Esker: Long narrow ridge of glacial debris that was left behind by an outwash that flowed under the glacier.

Esker

Braided Stream Braided Stream: Streams formed in glacial till that has a braided and irregular appearance

Delta

Delta and Braided Streams

Calving and Abduction Zone

Sea Ice Formation Frazil Ice (1) –Slushy salt water. First step to becoming Sea Ice

Grease Ice (2) –Forms when Frazil Ice begins to congeal forming a thin “greasy” layer on top of it.

Pancake Ice (3) –3 rd step in Sea Ice formation. Grease Ice sticks together forming small “pancakes”.

Sea Ice (4) –Frozen Salt Water. May or may not be attached to land.

Ice Shelf

Larsen B Ice Shelf (Antarctica)