Rockford Fossil Collection

By: Camryn Grawe

What is Rockford?

Rockford is a town in Iowa that was once under water. (pg 16) There is a quarry in Rockford that is filled with fossils. Before we look at fossils, we need to look at how Rockford was exposed.

Iowa Bedrock

The three main types of bedrock in Iowa is shale, limestone, and sandstone. (pg 16 and 17) Rockford is shale. Shale is formed in the shallow marine. (pg 14) The silt and clay washed off the beach, settled in the water, then went through changes. Some of the changes sediment can endure is heat, pressure, weathering, erosion, melting, cooling, and cementing. These are examples of the rock cycle, mechanical weathering, and geologic processes. (pg 10) Other kinds of known cycles are the water and reusing cycle. (See below) The rocks and fossils in Rockford went through very few changes because they are still loose from the ground and able to pick up. Therefore, the sediments didn't experience many of the usual cementing changes. Bedrock is layers of rock typically formed by water. In this case, Rockford's bedrock was exposed.

How Long Has Rockford Been There?

Scientist can tell the ages of rock by studying strata, absolute dating, and relative dating. (pg 18 and 21) Strata is like lasagna or laundry, layered from oldest rock on bottom to youngest rock on top (superposition). Absolute dating is the exact age of rocks in years, which can be found by carbon dating. Relative dating is comparing rocks to other organisms, not finding the exact age. Rockford was formed in the Devonian time period, so they age is about 416 million years old. (pg 17)
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Below is a gallery with explanations for five unique fossils that were found at Rockford Fossil Park.

What is a Fossil?

Fossils are remains or traces of ancient life. (pg 22) Fossils can also be body parts of organisms and traces such as, bones, shells, teeth, and leaves. These traces sit and accumulate sediment, harden, and fossilize. This fossilization process can be compared to face plaster and imprinting leaves in art.

Why Is This Geology Important?

Everyday life and the economy would be impossible without geology. (pg 6) Minerals make up many objects, such as water bottles, clothing, food, toothbrushes, and phones. Also, teaching and jobs make money from geology. A connection to this is when businesses and jobs decrease when materials are lacked, therefore taking a rapid downfall. All in all, we could not survive everyday life without geology.

My Thoughts: Then vs. Now

Early in the year, I knew we could learn about rocks by their fossilization and environment in which they came from. (pg 3) Now, I know much more. I understand the rock cycle, and the process of creating sedimentary (rocks in Iowa), igneous, and metamorphic rocks by weathering, erosion, heat, pressure, cooling, compacting, cementing, and much more. I now also can identify which environment a rock has been in, relative and absolute dating, layers of bedrock, fossilization, and why geology is important.


From rocks, we can learn how and where sediments gathered, cemented, deposited, weathered, eroded, fossilized, and formed...visit Rockford Fossil Park and Nature Reserve to get a real life look at all of these scientific explanations!