#4494 – rock on, rock out

so i’m reading my biology lab assignment (“identifying rocks”), and the lab manual isn’t written very well.

“Rock material that has been weathered, subjected to erosion, and eventually consolidated into new rock is sedimentary rock. Sedimentary rocks are classified into two types — clastic and nonclastic. Clastic sedimentary rocks are formed from the compaction and cementation of fragmented rocks. Nonclastic sedimentary rocks are formed from the precipitation of minerals in a solution.”

then a little further on…

“If the rock does not fit into the clastic classification, the rock is probably nonclastic.”

WHAT IN THE WORLD, LAB MANUAL. first you tell me “hey guys, there’s two types of sedimentary rocks!”, then you say “if it’s not one of these two types then it’s probably the other!”… is this science-book-writers’ version of sarcastic humor?

in other rock news, i’m coincidentally wearing my “study on. rock on.” shirt i got from apple for some reason or another.