Ad: Do Stratigraphy Because Geology Rocks T-Shirt Are you into stratigraphy the study of the different layers of rock on Earth? No need to be a die-hard geologist to enjoy any of these educational scientific gifts featuring the different rock layers found in the Grand Canyon along with the scientific truism saying "Do Stratigraphy Because Geology Rocks". Memorable layers of rock gifts for all! myGeology #stratigraphy #geology #words #TShirt