Study Reveals Stones Unique to Southern California March 10, 2021 Share This: As an undergraduate, geology alumna Sierra Patterson embarked on a study to help resolve an archaeological problem with geologic tools. Patterson, alumnus Ryan McKay and their faculty research adviser Valbone “Vali” Memeti focused on learning more about the mystery of cogged stones. These ancient Native American artifacts are found in Southern California, including Orange County. The cogged stones were carved from various rock types into the shape of a hand-sized cogged wheel. This basaltic scoria is a commonly used rock to carve cogged stones. One of the most commonly used rock types to carve the cogged stones is the basaltic scoria, a type of volcanic rock, said Memeti, assistant professor of geological sciences.