In the middle the downstream ledge of bridge 6, you'll notice a big rock that sticks out and up. This is a very nice example of Catalina Gneiss (gneiss pronounced 'nice'). Here's some info. You can remember bridge 6 by remembering that gneiss has 6 letters and/or that at bridge six, the gneiss rock sticks (out). Six rhyming (more or less) with sticks.