fossils+and+New+England's+prehistoric+past

=Fossils and New England's prehistoric past=

Hi my name is Byron and I’m an eighth-grader at the [|Amigos school], in Cambridge, MA. I’m creating this Wiki to teach the other people about fossilization and New England’s prehistoric past. Recently, my class went on a field trip to the [|Harvard Museum of Natural History], where we learned a lot about those topics.

In the Harvard Museum of Natural History, we used the students’ lab to take the “New England’s Prehistoric Past” class. There, we, using fossil samples and live samples filled out guided worksheets and took notes to learn about fossilization and New England’s prehistoric past.

One of the topics we studied was fossilization. Fossilization is the process by which ancient organisms are preserved and turned into rock. There are two types of fossils, fossil remains and fossil traces. Some examples of fossil remains are bones, horns, teeth and shells. Some examples of fossil traces are eggs, coprolite and tracks.

The first step of typical fossil formation is when an organism dies and is quickly covered with mud or sediment in water. Then the organism’s flesh (if it has any) rots, leaving the solid parts behind. Over many thousands of years, the minerals in the water slowly replace the minerals in the bones, turning the fossil into rock. Finally, erosion might expose the fossil to the world again, where us humans can find them. The study of fossils is called Paleontology, which gives us many insights into the past. However, fossils don’t give us a complete picture of the past because not all organisms fossilize.

In the lab, we used fossils to determine what New England was like in the past. Fossils from 600 million to 450 million years old told us that the ancient environment then was covered in salt water. We know the water was warm because of the presence of coral fossils. The absence of animals that burrowed tells us that the water was quiet and without strong waves. Other microscopic fossils tell us it was shallow water.

Then we used samples of New England igneous rocks, granite and basalt, that were between 450 and 350 millions of years old to determine what the New England environment of that time was. These igneous rocks showed us that around this time lots of volcanoes and new rock formed. The rocks at left and center are Granite. The rock on the right is basalt.

After that, we looked at 250 million year-old metamorphic rocks, marble and gneiss and a map of New England to determine what was happening during this period. Have you ever noticed that the mountains in New England are farther away from the coast than they should be? That’s because when Africa and North America crashed together they formed those mountains, creating many metamorphic rocks in the process. Later, between 220 and 190 millions of years ago, North America and Africa ripped apart again. However, a chunk of Africa was left behind, which formed part of eastern New England, including Cape Cod. We know that at this time the climate was wet and swampy because of the presence of fern fossils. Fern fossils tell us it was wet because ferns usually grow in wet and swampy areas. The tear in this map of southern New England indicates where Africa and North America collided to form mountains.

We know that in the last 190 million years, the mountains in western New England have eroded from 20,000 feet tall to 3,000 feet tall today. All the sand that now makes up New England’s beaches is till eroded from the mountains in western New England that was then carried by wind, water and glaciers to the beaches.

We also know from ice cores in the artic and glacier “tracks” (deep scratches in rocks caused by glacier) that from roughly 2 million years ago to 12,000 years ago, we’ve had several ice ages. Another indicator of the ice ages is the presence of fossils of very large, furry mammals from the ice ages. These animals were large and furry so that they could conserve heat better.

As you can see, I learned a lot about fossilization and New England’s prehistoric past on this field trip. I hope you learned a lot from my Wiki as well. Thanks for reading it.

-Byron