Sabino Creek

Today we visited Sabino Canyon, a National Recreation Area.

Sabino Creek begins 6,000 feet above the desert floor, in the pine forest that shades the slopes of Mt. Lemmon in the Santa Catalina mountains.

The rocks of the Catalinas are mostly granite and "Catalina gneiss," a hard metamorphic rock with a layered, or banded appearance. The gneiss was formed nearly a billion and a half years ago. At that time, a mass of molten rock cooled deep underground, forming a large layer of granite. Another mass of molten rock invaded the deeply buried granite about 45 million years ago. This second rock pooled in the granite in great fingers and sheets. Where they are visible today, these rock layers were stretched before they cooled and hardened, so that they layers are thin. The dark rock layers that we see today are the remains of the ancient granite, the light layers are the younger rock that invaded it 45 million years ago.

Entire mountain slopes in this Canyon display these stripes.