Bloomsburg Formation
From Wikipedia, the free encyclopedia
The Bloomsburg Formation is a mapped bedrock unit in Pennsylvania, New Jersey, New York and Maryland. It is named for the Town of Bloomsburg, Pennsylvania for which it was first described.
Contents |
[edit] Description
The Bloomsbrug is defined as a grayish-red siltstone, shale, and sandstone arranged in fining-upward cycles.[1] Although the Bloomsburg can sometimes be green to gray, its most dominate color is red and they are often called "The Bloomsburg Red Beds". This is signifcant in the Appalachian Basin since it marks the first large scale terrestial collection of sediemnts in the rock record. Most of the sediments that were deposited before this time were marine, or a small scale terrestial zone.
[edit] Depositional Environment
The Bloomsburg is mostly molasse resulting from the Taconic orogeny. The red color is often evidence that the sediments were deposited in arid conditions. The upper parts of the Bloomsburg are thought to be a marine transition zone.[2]
[edit] Fossils
There are numerous fossils found in the Bloomsburg, mostly in the upper parts of the formation. There are trace fossils of early land plants and brachiopod fossils in the upper marine transitional zones.[2]
[edit] Age
Relative age dating of the Bloomsburg places it in the Upper Silurian period, being deposited between 417 to 410 (±5) million years ago. It rests conformably a top the Shawangunk Formation and has a complex upper contact. In eastern Pennsylvania and New Jersey, the upper part of the Bloomsburg marks the Wallbridge Unconformity. As you move west, the Willis Creek Limestone lies conformably atop the Bloomsburg. Furthur west, the McKenzie Member of the Mifflintown Formation interfingers with the Bloomsburg and eventually, the Bloomsburg pinches out into the Mifflintown.[3]
[edit] Economic Uses
There are no known uses of the Bloomsburg stone except for its use as a local building stone.
[edit] References
- ^ Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000.
- ^ a b Hoskins, D.M., (1961). Stratigraphy and paleontology of the Bloomsburg Formation of Pennsylvania and adjacent states: G36. Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.
- ^ Berg, T.M., et al., (1983). Stratagraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.
