A combination of wind and water are eroding this glacial drumlin at Chimney Bluffs State Park on the shores of Lake Ontario. The glacial drumlin is made from fine sand and gravel and was deposited about 10,000 years ago at the time the glaciers receded from this area of New York State. The lake waves continue to remove material from the base of the cliffs causing more of the sand and gravel to fall into the lake. These eroded cliffs are very dangerous for hikers, since the ground continues to fall into the water.