Hard & Soft a Falls Doth Make: Roughlock Falls
🚙 US-14A Mileage 14.4                                          GPS Coordinates N 44.20.983  W 103.56.598    5.220 ft.
Hard & Soft a Falls Doth Make Update2.pdfField Exploration
Waterfalls – they seem to have an almost magnetic ability to draw the interest of the outdoor enthusiast and generate a sense of wonderment on the part of every observer. But why are waterfalls seemingly so rare and how exactly do they form? Roughlock Falls provides us with the ideal opportunity to investigate the geologic forces behind their formation as well as a chance to hear the roar and feel the mist of the plunging Little Spearfish waters as they impose their will upon the rocks below. Join us with camera in hand for this exciting lesson into the science that makes it all possible.
This pdf document contains the specific directions for reaching our featured Lesson Site as well as a detailed explanation of its geologic story. Mileage to the site as well as its specific coordinates are listed on the header above and also in the lesson document. Roadmaps and other learning aids can be found at the Lesson Resources link in the menu and are helpful to have handy in the field. Please print this document and take it with you or read it thoroughly before departing. Exercise extreme caution at the lesson site and along roadways.
Are you ready. . . . Let's Go!
S. V. Fogarty  &  W. R. Stevens
*Mileage starts at the intersection Colorado Bvd. and US 14A near Spearfish.
Little Spearfish Creek plunges roughly ~25 feet to the valley floor after passing over a ledge of resistant rock. Roughlock, like Spearfish Falls downstream, is amazingly persistent with consistent flows of water that are rarely interrupted.
This photo was taken from the observation deck on the south side of the falls. This is a great vantage point for viewing the plunge pool below. There are numerous hiking trails around the falls to provide a wide spectrum of viewing angles. The trail along the north side will take you to the lower reaches of the falls complex where you'll find a series of interesting small cataracts (little stair-step falls)Â in the stream. One can follow this trail all the ways to Spearfish Canyon Lodge if desired.
Stratigraphic Exposure
This vertical profile of rock is visible just across the roadway from the falls parking lot. These three formations dominate the immediate Little Spearfish Canyon area and represent a period time spanning 100 million years.
Roughlock Siltstone
A vertical cliff of the Roughlock Siltstone ( a member of the Ordovician Winnipeg Formation) is exposed along Little Spearfish Creek below the falls and is intimately involved in the formation of the falls itself. The siltstone can be viewed by walking the paved pathway downstream to a short bridge-crossing. Roughlock Falls is slightly visible to the left of the siltstone outcrop in this photo.