The granite that composes most of the Wet Mountains solidified some 1.7+ billion years ago, in the Pre-Cambrian era (essentially, before any life began on Planet Earth). It's the same age as the granite in the Blanca Massif. While most of this mountain range is Pre-Cambrian granite, there are a couple areas of Cambrian metamorphic rock (north and east of Lake DeWeese) and the rock deposited at the top of Greenhorn Mountain is only about 25 million years old and solidified about the same time as the Spanish Peaks and the Silver Mountain-Mt. Mestas group. The mining areas around Querida and Rosita are in rock about the same age as the top of Greenhorn (Oligocene/Middle Tertiary period).