Motherland EarthCache

About 100,000 years ago, glaciers stopped their descent into North America when they reached the Delaware area, before reaching Georgia.  Had they scraped their way through our southern state, they would've scraped off the surface soil and left us with huge swaths of exposed rock and thin soil as they did in New England.

Instead, we have regolith, a combination of weathered rock and acidic soil typical of the Appalachian Piedmont region – which stretches across North Georgia.

At home in this area, as vegetation dies back and your garden beds become bare, it's easy to notice that rocks are everywhere.  "In the Piedmont, the rocks you find in your yard are just bits and pieces of weathered rock, and you're most likely to find quartz-rich rocks because quartz is hard and the most common mineral," says William "Sandy" Schenck, a geologist and associate professor of geology at the University of Delaware.

This weathered rock, known as saprolite, yields up fieldstone.  Saprolites form in the lower zones of soil profiles and represent deep weathering of the bedrock surface.

In Lullwater Park, you can find very large pieces of granite saprolite, broken off from the underground granite sources and becoming exposed to the surface of the land as the soil erodes. There are fewer of these “fieldstones” today then before the land was quarried by people who were landscaping this historic park.  These people used the quarried granite fieldstone to build Lullwater House (Emory University President’s residence), line the roads and build research buildings that are now ruins.   

Now that you have learned about Lullwater’s large granite saprolite, take a walk around the park and observe the fieldstone and rocks quarried from this historic landscape.  At the coordinates you will find the edge of Chandler Lake, lined with this locally quarried stone.  Nearby, a scenic path surrounds the lake where you can see some more of this large saprolite.

Your Earthcache questions to think about on this walk are:

Where in the park do you think the most fieldstone would be found – at the top of the hills or at the bottom?  What that you have learned makes you think that?

What type of rock is the fieldstone in this park?  What other local landmarks have quarries for this type of stone?

Do you notice much fieldstone around now?  Why might this be?

What are two objects made of fieldstone that you see in this park?

Email the answers to the CO for smiley confirmation and Have Fun!