The Mt. Cuba railroad cut is narrow and deep, and much of the rock is covered with dirt and soot from the train. The rocks are interlayered gneisses and amphibolites, with gneisses predominating in the south end of the cut and amphibolites in the north end. Folding is well developed, but the angle of the sunlight as it shines on the walls of the cut will determine which of the folds will be the easiest to see. A 4" amphibolite layer outlines the fold in this part of the outcrop. Wonderful examples of the effects of rock type on folding styles can be seen in the cut and in many of the rocks piled north of the cut.

Map and image gallery of selected rock outcrops in the Delaware Piedmont.

Approximately 100 yards east of the tracks is one of the largest outcrops in the park. Here along the hillside, a thick layer of crinkle-folded, yellow-weathering gneiss overlies a layer of garnet-bearing quartzite and amphibolite. At the contact between the quartzite and the schist, a large piece of the quartzite has fallen out creating a small cave. Maybe Indians used this cave, but it is not very inviting. If you hit the black rocks with a hammer they will ring. Look for the tiny lavender garnets in the quartzite.

GeoAdventures are designed to allow the reader to learn about a particular geologic point of interest in Delaware’s Piedmont province and then take a short field trip to that area. Want to know more about the Wilmington blue rock or Brandywine blue granite? Take the Wilmington Blue Rock GeoAdventure and go see just what the blue rock looks like.

The Geology of Delaware is an online resource for information about the geology and hydrogeology of Delaware. Information on these pages is explained in general terms although common geologic terminology is used. This book covers the major important factors in Delaware geology as well as latest research. Additional information is provided at the bottom of some pages and on the last page of the book, More Information.