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Unformatted text preview: Continental Glaciers Processes and Features Strip away sediment cover and loose bedrock Create a rugged bedrock dominated rocky coast Produce irregular coast that contains few depositional features Beaches derived from local till deposits, form pocket beaches Fjords Fjords Valley Glaciers produce excavation due to: -plucking -abrasion -freeze and thaw Characteristics: -U-shaped -steep-walled -hanging valleys Fjords: Chile, Greenland Norway, Iceland Canada, Alaska Mountainous coasts Steep walls, Deep U-shaped Characteristics: End & Terminal Moraines End Composed of Till Formed by ice conveyor belt piling up sediment Forms the backbone of Cape Cod, Martha’s Vineyard, Nantucket, and Long Island Till consists of gravel in a matrix of sand, silt, and clay Patterns of End Moraine and Outwash Plain Development on Cape Cod B. Depositional Processes B.
Glacial Flow Meltwater streams Sediment incorporated into ice Layers of sand and gravel Ice acts like a Conveyor Belt bringing sediment to front When ice Stagnates, sediment accumulates producing Moraine consisting of till Water flowing from a glacier front produces Braided Streams Braided streams deposit sandy sediment forming an outwash plain
Moraines and Outwash Plains Outwash Plains Formed by braided streams Sediment derived from reworking of till, additional sediment from glacial tunnels Sediment Distribution: -boulders and large gravel left behind -sand and fine gravel deposited in a broad Plain -fine-grained sediment transported to the ocean Kettles: -formed in outwash plains -Deep ponds -Shallow wetlands, bogs O u tw a s h P la in s a r e fo r m e d b y th e d e p o s itio n s a n d a n d fin e g r a v e l b y m e ltw a te r s tr e a m s K e ttle s a r e fo r m e d w h e n ic e b lo c k s m e lt w ith in o u tw a s h p la in le a v in g a d e p re s s io n Boston Harbor Drumlins Boston R ew o r k in g D r u m lin s b y wave action produces Spits Spits connect in d iv id u a l drumlins to fo r m P en in su la s Drumlins Drumlins Oval shaped hills of till 1km long, 10s of meters high Formed Beneath the ice Form all the Topography in Boston Form Islands in Boston Harbor F o r m a tio n o f D r u m lin s Distribution of Drumlins around Boston Boston Harbor Bathymetry Peddocks Island Slate Island Grape Island C lew B a y, I r ela n d Drumlin Sediment Drumlin anchors barrier Till cliff is sediment source Boulder pavement offshore shows former size of drumlin Coastal Structures prevent erosion of drumlin but cut off sediment supply to the beach Thus, the beach disappears III. Drowned River Valleys III.
Delaware Bay Due to Sea Level Changes During lower sea levels river When ice sheets melt and
water is returned to ocean basin, sea level rises and floods valley producing valleys deepen and widen by riverine erosion Chesapeake Bay Drowned River Valley ...
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- Spring '11