Extensive trails within Larimer County's foothills natural areas provide year-round access to scenic landscapes harboring a wide diversity of plant and animal life. The landscape is a reflection of the underlying geology revealed by widespread rock exposures. In a short span of a few miles, a succession of tilted sedimentary rocks rising from the Great Plains lead to lower montane elevations where metamorphic and igneous rocks mark the beginning of Colorado geologic history.

Whether just beginning on your geologic journey of discovery, or are a seasoned geology enthusiast, this guide is a resource towards learning or acquiring a deeper geologic understanding and appreciation of the foothills. The guide is comprehensive in coverage, yet serves as a jumping off point towards further exploration of the many topics covered.

While simply reading the guide will be informative, it will be quite satisfying to get out on the trail and see the geology in person. I find, and hope you will too, a deeper connection with the landscape that comes with knowing the geologic history of the ground we walk and live upon.

Included are geologic cross-section and stratigraphic chart are fundamental references for knowing the rock unit names, ages, topographic expression, and locations with respect to the natural areas. Throughout the guide, geologic terms in bold font refer to definitions provided in the glossary. The document is full of figures and photos. Many of the figures are hand-drawn, others are modified from the literature.