The Big Cedar Ridge ACEC is on 264 acres of BLM-administered land southwest of Ten Sleep, Wyoming, in Washakie County, in an area of abundant paleontological resources, particularly fossilized plants. Fossilized plants were discovered in the Meeteetse Formation in 1990, and the area contains a complete and well-preserved late Cretaceous Period plant community. Sites with such in-place preservation of entire plant communities are rare.
Management objectives for the Big Cedar Ridge ACEC are to protect and maintain its paleontological resources and to provide educational, hands-on experiences for visitors and groups. Fossil collecting in this area is a popular recreational activity and a popular activity for school groups, paleontological groups, and university studies. The BLM allows for reasonable amounts of fossil collecting in this area.
The Red Gulch Dinosaur Tracksite ACEC is on 1,798 acres of BLM-administered land off U.S. Highway 14, approximately 10 miles east of Greybull, Wyoming, in Big Horn County. The Red Gulch Dinosaur Tracksite is the largest tracksite in Wyoming, and one of only a few worldwide from the Middle Jurassic Period (160 million to 180 million years old). The dinosaur tracks might have been made by at least two types of theropods, meat-eating dinosaurs that walked on their hind legs. Adding to its scientific importance, evidence from this location brings into question assumptions about the geologic history of the area during the Middle Jurassic Period; this location was originally thought to be an ancient sea. Dinosaur tracks in the area have been exposed to surface weathering for varying amounts of time, and new tracks are exposed each year. The ACEC is also important because of its extensive and unusual Middle Jurassic fossil occurrence. Fossil resources are found throughout the area and include abundant marine fossils such as belemnites, oysters, trilobites, brachiopods, and ammonites, and fossilized plants. In addition, the area consists of the Red Gulch Dinosaur Tracksite recreation area and a small portion of the Red Gulch/Alkali National Back Country Byway.
Management objectives and challenges for this ACEC are to protect and maintain paleontological resources. The application of foreign substances such as chalk, plaster, and soft drinks has damaged a few of the dinosaur tracks in this area; overall however, there remains little evidence of damage from humans or livestock walking on the tracks. The possibility remains people could remove or destroy tracks, although removal of individual tracks would be difficult because of the brittle limestone in which the tracks are found.
The Sheep Mountain Anticline ACEC is on approximately 11,528 acres of BLM-administered land north of Greybull, Wyoming. The ACEC is composed of a classic Laramide anticline, an upward folded rock structure often featured in geology textbooks. Researchers visit the ACEC and use it for educational field trips. This ACEC also contains several caves that provide recreational, educational, and research opportunities. Some of these caves are of scientific importance because they contain active thermal springs and therefore provide information about the formation of these types of caves and related features.
The management objective for this ACEC is to protect its geological features.
The Spanish Point Karst ACEC is on approximately 6,627 acres of BLM-administered land on the west slope of the Big Horn Mountains in Big Horn County. The area consists of deeply incised canyon and mountainous terrain, the Medicine Lodge and Trapper Creek WSAs (refer to Section 3.7.6 Wilderness Study Areas), several eligible and draft suitable WSRs (refer to Section 3.7.5 Wild and Scenic Rivers), four significant cave and karst systems, sinking stream segments, and regionally important groundwater recharge areas. Cave entrances, passages, and waterways in this ACEC serve as a receptacle and circulation system for fresh water originating in the highlands to the east on USFS lands. A portion of the water that circulates through the karsitic system is trapped in the carbonate rocks and recharges the widely used (by both municipalities and irrigators) and economically important Madison aquifer. There are recreational opportunities in the area because of its good access for the public, scenic values, and varied potential recreation activities (primarily hiking, rock climbing, and caving). Popular caves in the area include Great X, Tres Charros, Bad Medicine, and P-Bar.
Management objectives for the Spanish Point Karst ACEC are to protect the cave system, sinking stream segments, and groundwater quantity and quality services the area provides.