Ozark Glade (IMAGE) Washington University in St. Louis Caption A glade on Stegall Nountain looking toward Thorny Mountain in the Ozarks. The rock is rhyolite, ancient volcanic rock dating from the Precambrian period that was uncovered by millions of years of erosion. Hot, dry and covered only thinly with soil, the Ozark glades create their own desert-like microclimates and are home not just to collared lizards but also to scorpions, tarantulas and prickly pear cactus. Credit Alan R. Templeton Usage Restrictions please credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.