One of the things I like about living in the Pacific Northwest are glacial erratics. These can sometimes be large boulders that seem to be spread around at random … which is exactly the case. During the last ice age the glaciers carried these big rocks (or little ones) sometimes for hundreds of miles … and then dropped them where they were when the ice melted. Sometimes they can be traced to their point of origin by the type of rock or chemical compostion. The fact that there were this big rocks spread around was one of the reasons I ended up with a degree in Geology.