Gibbons has both written and illustrated this beginner''s book to caves. Starting with the simple basic facts (caves are holes in the ground, which come in different sizes,) she slowly ratchets up the information level. She clearly explains how limestone caves and crystals are formed. By the end of the book, youngsters will learn about cave creatures and human cave dwellers as well as safety rules for spelunking. It''s a useful introduction to the subject. 1996 (orig.