Glacial Geology of the Finger Lakes with a

Glacial Geology of the Finger Lakes (with a focus on Honeoye Lake)

Honeoye Valley Association Annual Meeting Saturday, July 13, 2019 Dr. Bruce Gilman Department of Environmental Conservation and Horticulture Finger Lakes Community College 3325 Marvin Sands Drive Canandaigua, New York 14424 Bruce. Gilman@retiree. flcc. edu

Acknowledgements • Dr. Richard Young, SUNY Geneseo • Dr. David Barclay, SUNY Cortland • Dr. Henry Mullins, Syracuse University and • Herman Leroy Fairchild, University of Rochester

THE PLEISTOCENE, “GREAT ICE AGE” A Very Different North America 20, 000 years ago

Landscapes covered by slowly flowing ice

Global temperatures were 7º to 14º C colder than today

Ocean levels fell by over 100 meters (300 feet)! A cycle that repeated itself several times during the Great Ice Age

Pleistocene Ice Ages starting ~2. 5 million years ago ending 10, 000 years ago Warmer & less ice Interglaciations Colder & more ice Glaciations Raymo, 1992

How extensive? • 10% of our modern landscape is covered by glacial ice. • During the Great Ice Age, 32% of the global land surface was covered!

Today Quaternary North America - Ron Blakey

20, 000 years ago Greenland IS Laurentide Ice Sheet Quaternary North America - Ron Blakey

Honeoye Region at the peak of glaciation Antarctica - Kevin Mc. Mahon

Ice Sheet Margin advancing across upstate NY Lake Uplan ds

Selective Linear Erosion • Glacial ice has a preference to move in pre-existing stream valleys aligned with basal flow direction – it’s the area of least resistance! • Any meanders in the original stream flow pattern are straightened out – glacial ice does not bend!

Selective Linear Erosion at work in the Finger Lakes

Finger Lakes Formation Story (pre-glaciation drainage patterns) Ontario basin R S G C I H B A

Finger Lakes Formation Story (ice sheet advance) Ontario basin R S G Pr l g o a l a i c s e lak I C es lak l cia la g o Pr H B A

Finger Lakes Formation Story (ice sheet maximum) Ontario basin R S G C I H B A

Finger Lakes Formation (Valley Heads Moraine deposition) Ontario basin R S G C I H B A

Finger Lakes Formation (Drainage Divide Today) Ontario basin R S G C I H B A

Water Erosion V-shaped rocky stream bed Ice Erosion U-shaped glacial sediment fill

The Finger Lakes Region contains 28 broad U-shaped glacial troughs, 11 of these valleys are doubly dammed (north and south ends) by moraine deposits and contain water!

Regional drainage at the time of Glacial Lake Honeoye

Alaska – Ice Park Campground Glacial Lake Honeoye Landscape, 12, 000 years ago

Giant Beaver

Ice Age Peccary

American Mastodon

Wooly Mammoth

Migrating herds of large herbivores I couldn’t resist – great movie!

Saber-Tooth Cat

Dire Wolf and Peccary

Giant Short-faced Bear

With the Predators came the first Americans, Stone Age hunters

THANK YOU for attending today’s annual meeting