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Monday, April 8, 2013

Rocks & Minerals

The Land Conservancy for SCC hosted our favorite geologist, Gale Blackmer of the PA DCNR, for the second Rocks & Minerals event at Bucktoe Creek Preserve. Gale led the first program last fall for the PA Master Naturalist group, and we were happy to have her back again. The group of eleven were tested at the beginning when asked to categorize an unidentified group of rocks. Some participants separated the rocks based on color, some on texture, and even some based on the weight. We learned that identifying rocks is a detailed process, which is often determined by testing of the chemical structure. However, there are a few ways to narrow it down using a few simple tools. Visit this website that will help you ID a rock step-by-step:

Gale Blackmer and two participants identifying rocks.
Metamorphic rocks made of quartz, feldspar, and granite.

There are three fundamentally distinct rock types called Metamorphic, Igneous, and Sedimentary. Overtime, rocks go from one type to another in a process known as the rock cycle. Generally, rocks are initially formed from cooling magma above or below ground, which are called Igneous rocks. Once exposed to Earth's surface, weathering, water, erosion, heat, and pressure can transform an igneous rock into a sedimentary or metamorphic rock. Below is simple diagram showing the cycle: 

Credit: Center for Educational Technologies and the COTF/Classroom for the Future. 

Along Chandler Mill Road we visited a large outcrop, which is a patch of exposed bedrock that allows geologist to study the history of the land.

Participant inspecting the outcrop.

Full view of outcrop. 

For more information visit the PA DCNR Geological Survey website:

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