Just a few years ago, there was no such thing as an iPad or an iPhone or any of the apps that go with them. But now, millions of people worldwide are using more than half a million apps on a daily basis. One of the latest to debut on the iPad was designed by Flagstaff geologist and photographer Michael Collier. He takes aerial photos of mountain ranges and geologic formations across the country. And he does it while solo-flying his small plane. Collier's photos have been the subject of several books. And now his new iPad app, Wonders of Geology, makes the photos comes to life with text, audio and interactive geology. Arizona Public Radio's Gillian Ferris Kohl spoke with Michael Collier about what it's like to have his photos go electronic.