Gaines Tidwell

Pensacola GeologyPart 1

  This first part of my expedition proved to be an initially confounding one.

I’ve been back to Florida every year since I lived in Lemoore and I really couldn’t think of a good place to get some natural rock samples. I know how to easily get seashells from the beach but our beaches are not rocky. Finally I remembered on area that would be a good sampling area with (hopefully) plenty of variety. This area would also be my main area for the next part of this assignment as well. The area I surveyed was actually the area near my uncle’s house. He lives right on the water in the bay with water on three sides of the house erosion is a constant concern. To help combat the constant wave action and forthcoming erosion a large line of rocks has been placed on the shore. Not all of these rocks are from here I’m assuming because some preliminary research revealed that igneous and metamorphic rocks are not found on the surface of Florida naturally.

My sampling was quite varied in texture, size, luster, grain size, hardness, and color. Figuring out age was quite difficult as all of my samples were on the surface and probably artificially placed. I also could not find a exposed layers so I could not approximate the age of my sampling area.

Identifying Samples

This coarse rock was a small sample I found amongst the wide range of rocks along the shore. Its dark shape and and weight were helpful in identification. The porous holes seen were of some interest and after some research I think this may be the igneous rock peridotite.

Sample 1

Sample 2 was an interesting find. It had variations on color and ridges over a large portion of the sample. In some areas a black and white mixture suggested it contained calcite. With it’s soft hardness (for a rock) and coarse grains I believe this to be the sedimentary rock limestone.

Sample 2

Sample 3 was a large rock. One I didn’t even try to pick up, but instead used it as a stepping stone. The term stepping stone is what helped me identify it almost right of. This foliated, fine grained rock is what I believe to be the metamorphic rock slate.

Sample 3

This next sample is one that was quite common within this area. It’s mixed variation of rounded rocks within immediately led me to believe this was a sample of the sedimentary rock conglomerate.

Sample 4

Sample 5 is somewhat of a mystery for me. This rock was quite strange. It was very light and could be described as flakey and coarse. I was half tempted to throw it into the water to see if it would float. I still am unsure what this rock is and the blurry photo does not show the detail as much as I had originally hoped. Sample 5 may be an igneous rock or perhaps something else entirely.

Sample 5

The area I sampled from is quite an interesting one. It could be considered an artificial peninsula as the canal on one side makes it so that there is water on three sides. Water is the biggest feature in this area and it also plays into the geology of area a great bit. Just in the last 10 years the shore has been pushed back so far that the small road occasionally floods due to stormy weather. The rocks are in place to help slow the inevitable erosion which will be covered in part 2. The rocks I sampled as well as the rest of the rocks there are subjected to the water on a regular if not constant basis.