Geology of Garden Park

Garden Park was named for the farms that supplied fresh vegetables to the mining camps in Florence and later to the Cripple Creek Mining District via the Shelf Road, which runs northward from Cañon City, through Garden Park, to Cripple Creek and Victor. The Garden Park area was formed by a large fault-bounded depression that has created a valley on the north side of the Cañon City Basin. Pre-Cambrian crystalline rocks occur outside the valley as mountains to the east, north, and west of Garden Park, and within the structural depression a sequence of Ordovician, Mississippian, Pennsylvanian, Jurassic, and Lower Cretaceous sedimentary rocks is exposed.

At the southern access to the Garden Park area a large hogback, which is formed from the Cretaceous-aged Dakota sandstones, is inclined to the south.  Dinosaur footprints are revealed in these sandstones along the roadside known as Skyline Drive. The Morrison Formation occurs as low badlands along the valley of Four Mile Creek that eventually opens up into the wide valley of Garden Park. The original Garden Park farms were located slightly north of the Morrison Formation exposures where the erosion of the Pennsylvanian-aged Fountain Formation has formed a wide valley floor.

Badlands of the Morrison FmAlong Four Mile Creek,  the Morrison Formation is locally covered by large Dakota sandstone blocks that have slid downward and broken apart during a series of huge landslides. These large blocks came to rest on a surface within the middle of the Morrison Formation where swelling clays of the purple and red upper Morrison mudstones overlie a sequence of non-swelling clays that make up the greenish-gray lower Morrison mudstones. Landslide debris covers most of the Morrison exposures, except along badland gully wall and ridges. The dinosaur quarries occur in these Morrison outcrops.

The Morrison Formation has been interpreted as representing slow-moving streams or rivers that had extended periods of flooding and drought. The rock is varicolored, with maroon shale at the top and green shale at the bottom, and is interspersed with thin beds of limestone. The limestone beds have been interpreted as extensive lakes that filled the area at various times. A number of thick sandstone river channels are located at the bottom of the formation. Within the Garden Park Fossil Area the Morrison Formation is over 300 feet thick and fossils can be found throughout the formation.

The stratigraphy column illustrated below shows the sequence of formations in the Cañon City Basin.

Canon City Basin Rock Column - compiled by Emmett Evanoff, 1996.

References:

Information on geology from Geologic Guidebook to the Gold Belt Byway, Colorado, edited by Thomas W. Henry et al., (Gold Belt Tour Scenic and Historic Byway Association: Gunnison, Colorado. 2004).