The rocks exposed at Cave Point date to the Silurian Period, about 435 million to 410 million years ago, when this area lay near the earth's equator beneath a tropical sea where coral reefs thrived. Over millions of years, the remains of marine plants and animals and calcareous sands accumulated, and compaction and chemical alteration formed the dolomite bedrock now exposed there. In Wisconsin and across the Great Lakes region, these Silurian rocks appear as resistant dolomite layers that form a line of bluffs known as the Niagara Escarpment, with the same series exposed at Niagara Falls. Much later, the most recent glaciation of the northern hemisphere sent continental ice sheets repeatedly across the Upper Midwest, and their scouring and drainage systems helped form the modern Great Lakes while accentuating places such as Door County and other prominent rock outcroppings. As softer rocks and sediments were stripped away, the harder dolomite remained and was further shaped by thousands of years of wave erosion into the jagged cliffs and sea caves seen at Cave Point. The landscape continues to change through wave action, freezing and expansion of water in rock openings, gravity, and dissolution, the chemical breakdown of bedrock by water.