Okay I played around with Chris' idea this weekend while on a very casual, day hike with my wife and son. I unfortunatly didnt have 8 hours to devote to the project but I did pay close attention to the environment (particlarly the various soils) throughout our hike. We were on a very short (2mile) hike (because my son is only 22months old) and in that time we crossed everything type of soil from moist dirt, to sand, to rock. Widely varrying terrain is the one of the attractions of these particular trails. We mostly do these short hikes to give the kid a chance you play with twigs and flowers and throw pebbles in the river and creeks (which is his favorite). Needless to say, with a curious 2 year old boy we stop several times even on a 2 mile hike. What we are doing cant even really be called hiking but rather more accurately "playing in the woods". Anyway, one thing I did was sharpen a small stick on our first stop and then use it to dig a small hole everywhere we stopped along the trail. It didnt take long to prove true what Susan has already stated which is that the best place to find the right soil (atleast when only digging shallow holes) is near the water. My next project now is to see if I can actually construct and fire a natural clay pot with only firemaking supplies and a knife. I'll let you know how it goes.