Over hundreds of millions of years, rocks that were once covering this batholith eroded away. As the land continued to rise during the Laramide orogeny, further erosion occurred until all that remained were the granitic rocks.[5] The ice ages beginning 500,000 years ago began carving the rocks into their present shapes. Within the Winds, numerous lakes were formed by the glaciers and numerous cirques, or circular valleys, were carved out of the rocks, the most well known being the Cirque of the Towers, in the southern section of the range.