Diane Nelson Spickert has been a geologist for more than 20 years. She has enjoyed volunteering as a guide for Dinosaur Ridge in Morrison, Colorado, and teaching geology at local elementary schools. Marianne D. Wallace is a natural science illustrator and writer whose work has appeared in over 30 books and publications. She has also been an elementary school science teacher, a botanic garden tour guide, and a writer for the US Forest Service. She lives in the foothills of Southern California.