23 November 2010
Earlier this year, I took a (long) drive away from Buffalo to go visit some of the glacial features that “upstate” New York has to offer. Chimney Bluffs State Park is located on the shore of Lake Ontario in Sodus Bay (about halfway between Rochester and Oswego), and it’s an excellent place to see a truncated drumlin.
New York has a lot of drumlins, and if you make it out of the Hudson lowlands, they’re not hard to find; Callan at Mountain Beltway wrote about them last year as part of his trip to visit another SUNY school in Oswego. Drumlins are glacial features, long hills made of glacial till (unsorted sediments). They have blunt ends that point toward the glacier source and gentle slopes that point ‘downstream’ in the direction of glacier movement. There have been a lot of different explanations for their formation, but an Icelandic glacial field now has some geologists thinking that drumlins may be formed during glacial “surges”, periods when a glacier advances at up to 100 times its normal pace. (See Ole Nielsen’s recent post on this research for a better summary!)
According to my Upstate New York Geology Field Guide, the drumlin at Chimney Bluffs State Park is mainly composed of fragments of (local?) red sandstone, limestones, dolostones, and chunks of Canadian metamorphic rock in a sand-silt-clay matrix. The matrix accounts for the “chimneys” at Chimney Bluffs, which are representative of badlands-type erosion (where there is no vegetation to stabilize the sediments and they erode easily, in this case because of wave action from the lake).
Unfortunately, it being March when I made this trip, it was just a tad too icy to go down on the beach for a close-up look, but I did get some good views from the (very soggy) trail above the bluffs.
Most of the drumlin is (like all unsorted sediments) a massive deposit, but there seems to be a bit of layering near the top of the cliffs.
Of course, it’s also a good idea to keep away from the edge of the cliffs, because they’re constantly crumbling. You can hear rockfalls going on whenever you’re near the edge, and on this day (where a lot of snow was melting), it was easy to see little debris flows tumbling down the slopes.
Most of the rocks in the till are pretty small, but occasionally there are some big boulders, like this one (probably about the size of an exercise ball):
Here are a few pebbles I picked up from the path:
Despite the snow, and the soggy trails, and the threat of cliffside collapse, it was a nice hike, and a pretty park – one that was sadly deserted on what ended up being a pretty warm day. Go visit if you get a chance!