Post date: Jul 6, 2013 6:12:17 PM
This Tuesday, we changed up the usual pace: instead of collecting data and measuring fossils, we went to Brighton beach and Bean Hollow. A day in the History of Life program is filled with measures of fossils in books, but on our field trip, we were able to see them intact in their natural habitat! J
At Brighton beach, which approximately dated to 1.8-5.3 ma, (pretty recent), we were saw thousands of fossils preserved in the outcrop, which is essentially a visible rock formation. In addition to seeing preserved fossils in their natural habitat, we were able to the homes of ghost shrimp. Ghost shrimp are unique critters which burrow into the earth and in order to keep their tunnels open, the shrimp line the sides of the burrow with their fecal pellets. Also, in some the crevices, we were able to see isopods, the living relatives of trilobites. Trilobites, which roamed the earth many a moon ago, went extinct after the Permian, had compound eyes and dozens of tiny wriggling feet. The isopods share remarkable resemblance to trilobites compared to any other marine invertebrate. This particular beach was home to thousands of fossils—of specimen and their tracks (trace fossils).
Pebble Beach was much, much older than Brighton beach. As soon as we arrived, we noticed several differences from the previous beach. First, the rocks on the beach were shifted and instead of standing upright, the rocks were on their sides, suggesting that this beach had to be older than 10 million years. The other interesting aspect of this beach was that it was covered with not only sand, but with pebbles. Where did these pebbles come from? We were all puzzled with this phenomenon and even while exploring the intertidal zone, I was curious to find the origination of these pebbles. Turns out that the pebbles were fragments from conglomerate rocks, sedimentary rocks with sharp angles, which were formed with erosion!
Another major difference between Bean Hollow and Brighton beach was the intertidal zone. We were actually able to see actual living echinoderms like sea urchins in the intertidal zone. These animals, including various types of crabs and gastropods (snails), were well adapted to their environment. With waves constantly crashing down on them, some these animals, like barnacles are able to stick on the rocks without being swept away. Even the crabs were able to hide in between the tight crevices quite easily! Unfortunately, we were unable to see any asterozoa (starfish), another animal apart of the echinoderm phylum.
The field trip was an excellent getaway: the weather was cool, the ocean was beautiful, and it was a great way to learn about the formation of fossils and experience the habitat of these neat organisms! I can’t wait for our next field trip!