This is a piece of Homewood sandstone with load casts. Load casts form when dense, overlying sediments settle into less dense, water-saturated sediments below. This specimen measures approximately 15 cm long X 6 cm wide X 4 cm tall. Specimen is very fragile, and crumbles readily.
- Catalog Number:
- 45522
- Object/Specimen Description:
- Specimen Count:
- 1
- Precise Locality:
U.S. Route 48 west of Pisgah Road bridge
- Locality:
- US Mid Atlantic (PA, NJ, MD, DE, DC, VA, WV)
- Collecting Locality:
- North America, United States, West Virginia, Preston County
Sedimentary rock formation, southwestern Utah, USA
Courtesy of Mark A. Wilson, The College of Wooster
At or near Earth's surface, sedimentary rocks form in two ways: by the accumulation of rock grains or by the formation of a solid from minerals dissolved in water. The fragments that go into making sedimentary rocks can be as big as boulders or as small as clay particles. Over long periods of time, the upper layers of debris compress the lower layers, squeezing out excess water or air trapped between the rock fragments. Under the pressure, individual fragments eventually dissolve and stick together, or the remaining fluid within the sediment brings in other substances that act as a cement, until the sediment has turned into rock. Scientists classify many sedimentary rocks based on the size of the particles that built the rock; mudstone and sandstone, for example, originally came from fine-grained mud and sand deposits that hardened over long time periods.