The outstanding geologic features of the park are the ancient sedimentary beds of deep-red, pink and white sandstones, conglomerates and limestone that were deposited horizontally, but have now been tilted vertically and faulted into fins by the immense mountain building forces caused by the uplift of the Rocky Mountains and the Pikes Peak massif. The following Pleistocene Ice Age resulted in erosion and glaciation of the rock, creating the present rock formations. Evidence of past ages can be read in the rocks: ancient seas, eroded remains of ancestral mountain ranges, alluvial fans, sandy beaches and great sand dune fields.