Quaternary Geomorphology A Workshop for P G Candidates

Quaternary Geomorphology A Workshop for P. G. Candidates December 18, 2010 Dr. Don Thieme

• Geochronology, Glacial Intervals, Isotopic Dating, etc. . . • Glacial Landforms and Sedimentary Deposits • Soil Classification and Paleosols • Sea Level and Coastal Geomorphology

Glacial Landforms and Sedimentary Deposits

Glaciers • glaciers form where snowfall is high and temperatures low high altitudes (alpine glaciers) • high latitudes ( ice sheets) • • accumulation – addition of snow to a glacier snowfall • rain • • ablation – the loss of snow and ice from a glacier melting • sublimation • calving •

Alpine Glacier Profile

• Inputs (zone of accumulation) vs. Outputs (zone of ablation) • Three Possible Situations: Inputs > outputs - advancing glacier till plain end moraine Inputs = outputs – stationary glacier Inputs < outputs – retreating glacier

Ogives “waves” or “bands” of ice annual features useful for calculating velocity of glacial advance and retreat also indicate glacier base and margins Ogives icefield near Juno, AK

Esker in former glacial lake, Waterford, Maine

Esker near Dahlen, North Dakota

Eskers - subglacial origin Esker fill near Plattsburgh, New York showing “openwork” (clast-supported) gravel overlying coarse sand beds

• "morphosequence" of glacial and proglacial landforms • all deposits laid down as the ice stood at a mappable location on the Earth's surface. • proglacial deposits are supplied by the "dirt machine" that occurs where live ice rides up over stagnant ice.

Proglacial rivers or lakes may begin directly in front of the stagnant ice: (A = fluvial ice-contact; C = lacustrine icecontact). Proglacial lakes may be fed by meltwater rivers (D = Fluvial lacustrine ice-contact)

Rivers may be fed by water from a proglacial lake through a spillway (F = Lacustrine fluvial ice-contact)

• • glaciers dam pre-existing rivers glaciers depress the land surface, forming new lake basins glaciers produce moderate to large volumes of water during spring thaw continental glaciers produced particularly large volumes of water when they melted back during the late Pleistocene

Nellie Juan Glacier and terminal moraine, Prince William Sound, Alaska. (http: //pubs. usgs. gov/of/2004/1216/m/m. html)

Ohio and Missouri Rivers follow ice margins Glacial Lakes occur north of both rivers No Glacial Lakes south of these rivers

Varves in a Swedish glacial lake Climbing ripples from an icecontact delta in Rhode Island

• The "channeled scablands" in Washington state were formed by outburst floods from proglacial Lake Missoula

Shelbyville Carbondale

Devensian glaciation (OIS- 2, 4) followed by the Flandrian transgression (OIS-1) in England, Wales, and Scotland