Glacial Landscapes Glacier = large moving mass of ice. Glacier = large moving mass of ice. Glaciers erode, transport and deposit massive amount of sediment called till. Glaciers erode, transport and deposit massive amount of sediment called till. Important to NYS. (last ice age was 10,000 y.a.) Important to NYS. (last ice age was 10,000 y.a.) 2 Types of glaciers: 2 Types of glaciers: Valley glaciers Continental glaciers

Valley Glaciers Smaller scale glaciers that form at high elevations. Smaller scale glaciers that form at high elevations. Flow starts when accumulated snow and ice becomes too massive and flows. Flow starts when accumulated snow and ice becomes too massive and flows. Speed of flow is dependent on slope of valley floor. Speed of flow is dependent on slope of valley floor. Sides and bottom of valley glacier move slower than the middle. Why? Sides and bottom of valley glacier move slower than the middle. Why?

Continental Glaciers Glaciers that cover broad, continent sized areas. Glaciers that cover broad, continent sized areas. These glaciers move because they are very thick in the center and flow out from that thick center point. Why? These glaciers move because they are very thick in the center and flow out from that thick center point. Why? The Laurentide Ice Sheet covered NYS about 10,000 y.a. The Laurentide Ice Sheet covered NYS about 10,000 y.a.

Glacier Movement Advance – glacier moves forward. Advance – glacier moves forward. Retreat – glacier appears to move backward. Retreat – glacier appears to move backward. In reality during a glacial retreat, the glacier is still moving forward under gravity, but it is melting faster that its forward motion.

Glacial Deposition Most glaciers push, carry and drag great quantities of sediment. Sediments carried by glaciers or the melt-water of glaciers is called glacial drift. There are 2 main types of drift: 1. Once a glacier retreats the unsorted material deposited directly by the glacier is called till. 1. Once a glacier retreats the unsorted material deposited directly by the glacier is called till. 2. Sorted material deposited by the melt- water is called outwash. 2. Sorted material deposited by the melt- water is called outwash.

Glacial Deposition

Moraine – small ridge of till left over by glaciers. End moraine – small ridge of till located at the front of a glacier. Terminal moraine – small ridge of till left at the furthest extent of the glacial advance. Recessional moraine – a series of ridges left behind as the glacier retreats. (formed during pauses)

Glacial Deposition Lateral moraine – small ridge of till left at the sides of a glacier. Medial moraine – small ridges of till formed at the meeting point of two valley glaciers (center). Ground moraine – low mound of till left behind under a glacier. Drumlin – oblong shaped hill formed during a glacial retreat.

End Moraine and Lateral Moraine

Lateral moraine and Medial moraine

Retreating glacier and ice-marginal lake

Drumlin

Glacial Deposition Outwash plain – plain of till in front of glacier, fed by melt-water. Kettle – depressions left in the outwash plain by large blocks of ice that break off the glacier. Esker – winding ridge of till that has filled in an old melt-water tunnel. (formed under a glacier)

Outwash and braided melt water channels

Kettles

Esker

Glacial Landscapes on Mountains Cirque – deep depression carved out of existing mountains by valley glaciers. Horn – steepened peak left behind after a glacier erodes a mountain on 3 sides. Arete – A ridge of mountain left behind after glacial erosion, usually forming where two cirques on opposite sides of a valley meet.

Cirque and horn

Aretes

Glacial Landscapes Other Important Points to Know: 1.Glaciers carve “U-Shaped” valleys as they erode. 2.Glacier can leave behind parallel scratches in solid bedrock called “striations”. 3.U-Shaped valleys that meet or join into other lower valleys can form, hanging valleys that rise higher than the lower valley.