Existing comment:
Layers of Time:
Take a close look at the cliffside above you. Become aware of layers in the rock. Each one of these strata was laid down in a different time period, during a processing beginning ten million years ago at the bottom of an enormous lake.
Over eons, earth-pressures beneath the lake gradually changed limey mud layers into solid rock -- a limestone that geologists now call the Verde Formation. Over more eons, the lake drained. The Verde River and its tributaries cut channels through the dry lake-bottom sediments. Then wind and water began sculpting the caves and crevasses we see today in softer limestone layers. |