Sampling the subsurface: 6 of 10

This is a picture of the cap that is attached to the end of the sampling pipe. In this photo, it is filled with material because it was just removed from the end of the sampling pipe from the 4th picture in the series. There is a sharp edge around this cap, which cuts the ground and forces the material into the sampling pipe, which contains the sampling tube. The geoprobe (machine we used) uses hydraulics to push the sampling pipe through the unaugered ground. In an ideal world, sharp edge on on the end of the sampling pipe cuts the material and and as it’s pushed deeper into the ground undisturbed material slips right up the pipe into our plastic sample tube. In reality, the pipe catches small stones or hard material that might compact or even impede our ability to push and collect a sample. In this image you can see the material we are pushing through. We call it saprolite, which is essentially weathered granite. You can see there is fine grained material and large feldspar crystals (pink pebbles) intact from the original granite. I poured some water on top of this material and it flowed through. So although this looks hard, it is actually porous and permeable.

 

Done