2013 Guilford Quartz Monzonite
Patapsco Valley State Park
Ellicott City Granodiorite
New York trip


I visited the old Guilford Quarry on January 12, 2013, where the Ordovician Guilford Quartz Monzonite was extracted from the earth for building stone, mainly in the late 1800's. The quarry is now flooded. The first photo shows a view from Guilford Road in Kings Contrivance Village, facing the north wall. I collected two specimens there (gq1 and gq2).

There are boulders of the monzonite around the quarry and in other areas nearby, such as between a bike path and the Middle Patuxent River in Columbia, as shown in the second photo.



I visited the Hilton area of Patapsco Valley State Park on March 9, 2013. The ground surface is covered by boulders and cobbles of the Mount Washington Amphibolite of the Baltimore Mafic Complex (which used to be called the Baltimore Gabbro Complex) in many areas, with some conspicuous quartz as well. We also came across a large boulder of pegmatite, shown in the first image, and I collected several specimens there (pr3, pr4, pr5, pr6, pr7). The other image shows one of the larger amphibolite boulders there.
The pegmatite boulder is located at GPS 39.247335, 76.747203








On a bike ride around Lake Elkhorn in Columbia, Maryland, on May 5, 2013, we stopped to look at a striking outcrop of schist with some prominent veins in it.

The first image shows the outcrop from the bike path.

The second is a mosaic of two images, with my son for scale.

The third is a closeup of the pegmatite vein.

The last one shows one of the veins on the top of the outcrop, looking down.

GPS 39.184159, 76.835355









I visited Ellicott City, Maryland, on May 18, 2013, to look at some old quarries of the Ellicott City Granodiorite that I had been reading about. We went to an outcrop behind the Fireside Stone and Patio shop, which is on the Baltimore County side of the Patapsco River. I collected one hand sample (ecg1) from the outcrop.

The first image is an overview of the old quarry wall.

The second one shows a prominent pegmatite vein near the base of the outcrop, with a US quarter for scale.

The third one shows an exposure with lenticular variations in the granite texture and color.

The last one shows some prominent diagonal jointing in the wall.





In October 2013, we traveled to New York for a friend's wedding but stopped to see some interesting geology along the way. These images are from Mendon Ponds Park near Rochester, where you can see a lot of glacial landforms. I had never walked along the crest of an esker before, and that is what the steep hills are in the panoramas. They are on the Devil's Bathtub trail, and Devil's Bathtub itself (a kettle) can be seen on the right side of the second image.























These images are from the remarkable Watkins Glen State Park, south of Rochester, New York in the Finger Lakes region, also taken in October.