We'd also like to create a "20,000BC" level to show how Manhattan looked during the last ice age, when it was covered by the 300-600m thick Laurentide Ice Sheet. This could be a lower-resolution version of the landscape (since users won't be able to "walk around" under the ice) and optimized for animating the glacier's advance and retreat.

Ice Thickness: ~300m

Estimates vary, but let's assume the thickness of the ice sheet over Manhattan as of 20K BCE was **300m **(1000 ft). The ice sheet was up to 2 miles (3200m) thick in places, but likely much thinner at the "edges". Manhattan was near the edge of the ice sheet.

Reference Videos and Articles

• Video animation of the retreat of the Laurentide Ice Sheet
• BBC documentary on formation of Manhattan
• "How the Ice Age Shaped New York" (New York Times) - claims thickness over Manhattan was 1000-2000 ft (300-600m)
• "The Ice That Made Manhattan" (Columbia University)
• "New York City in the Ice Age"
• Wikipedia on Laurentide Ice Sheet
• Great video on the formation of Long Island by glaciers

Reference Images

Actual glaciers in Greenland:

Sea Levels

• 12,000 years ago, the ocean level was about 70m lower than it is today
• This would have exposed the continental shelf off New York (aka the "New York Bight")
• Note that the Hudson river actually carved a canyon in that shelf that is still visible today underwater!

• This canyon is visible in our 12K BC Level as well. Need to make it 3D and play with the water level

Front end calving: https://youtu.be/hC3VTgIPoGU?si=mDqMVrNDL7y7CEgE&t=84

Google Maps views of Antarctican glaciers/ice sheets:

Ice sheets flow around higher mountain ranges. The Laurentide ice sheet was 600-900m high, so it was below most of the red areas in this image (i.e. flowed around them):