Two Arkansas alumni, Michael Slay and G.O. Graening, and their colleague, Danté B. Fenolio, will talk about their new book, Cave Life of Oklahoma and Arkansas, at 7 p.m. Thursday, April 26, at Nightbird Books, 205 W. Dickson Street in Fayetteville.

Slay is the program director of Ozark Karst for the Ozark Highlands office of the Nature Conservancy, the host for the presentation. Graening teaches at California State University, Sacramento, and is founder of Natural Investigations Co., an environmental consulting firm. Fenolio is a photographer and amphibian conservation scientist for the Atlanta Botanical Garden.

Cave Life, published by the University of Oklahoma Press, gives readers a look at what's crawling, swimming and flying somewhere beneath the surface. The authors began research for the book in the early 1970s as part of a study of Ozark cavefish but expanded to include a number of subterranean research topics.

The authors and their team donned snorkeling gear, cave suits and rock climbing harnesses, descending into caves in Oklahoma and Arkansas to study and inventory cave animals.

Subterranean organisms are key indicators of groundwater quality, the authors say, and so understanding what is happening with them is one more way of understanding what's happening above ground.