The hill in this photo is a large cuesta known as Como Bluff. It’s about a mile north of the path of the Union Pacific Railroad, and railroad personnel found rich fossil beds in the northwest face of the hill – the one seen here – during construction. There followed a scramble by competing groups of paleontologists to identify new species, which came to include a large fraction of the dinosaur species that you learned about as a child (especially if you’re over the age of 50) and apparently almost all known Mesozoic mammal species. The competition was sufficiently fierce that rival groups sabotaged each other’s quarries. The accessible fossil beds all got mined out in the 1800s, and today Como Bluff is private land, not accessible to the public.