This morning we headed to two spots, Rice Bay and North Point. We took the truck to Rice Bay first which is part of the North Point Member. The North Point Member is entirely made of eolianites, which are ancient lithified sand dunes. There were climbing beds of ripples which Jill told us were preserved because of how quickly carbonate rocks can be formed in this environment. In other sedimentary rocks, the layers could have taken millions of years to form, but these layers were able to be cemented in just a few days. The carbonate sands mixing with acidic rain causes lithification to happen much quicker than in other systems. That rapid lithification allowed ripples dunes to be help in place, and ultimately preserved so that we can see them today.
I also thought it was very cool that we were able to see evidence of ancient processes and see those same processes happening today in the same site. One example is how we saw trace fossils of plant runners in the rock and plants were still growing all around the area. We also were lucky enough to see a ghost crab’s tracks and ripples left by the wind (picture is of ghost crab tracks).
Animal tracks and ripples are processes that happen on earth everyday, but are also things that can tell us a lot about the earth millions of years ago. I think an experience like this bolsters the idea of uniformitarianism (processes happening in the present also happened in the past), which is central to earth science. At North Point we were able to walk all the way out to the edge and see Cut Cay, both of which have some of the highest elevations on San Salvador (photo of Cut Cay from the edge of North Point).
On the way there, we made note of the difference between the east and west sides of North Point. The east side was almost devoid of vegetation and was being battered by waves. The west side was covered in green vegetation and was much calmer. You can see the color difference in the water from the east and the west side. The east side is darker and therefore deeper. The west side is lighter in comparison, meaning there’s a stretch of shallow water, which slows down the waves and makes it so they don’t crash on the shore (pictured first: east side, pictured second: west side). Overall, the morning was a super cool experience and I learned so much in so little time. I think it was a great way to start our time here at the GRC.
-Contributed by Sara
Photo credit: Sara
Comments