Neuropteris stem-- inner pith cavity and outer cortex

 

Rock Type: Gray shale outside, sandstone inside
Formation: Allegheny
Interval: Middle Kittanning Seam
Age: Middle Pennsylvanian Period, approx. 301 million years.

This rare specimen illustrates a sandstone cast of the inner pith cavity surrounded by a shale cast of the outer cortex layers. Usually only the inner pith cast is preserved.

It is important to remember that when stem and trunk specimens of the various forms of non-silicified plant fossils are found they are usually in fact casts of the hollow inside of the plant only.

Occassionally, as here, part of the outside cast is preserved. Almost always when this type of preservation is found the plants were standing upright during burial. As a consequence, as the muds and silts around them compacted and dewatered, they left grooves or slickensides on the outer surfaces, as seen on the outer cortex of this specimen.View a close-up image.


Location: Wayne County, West Virginia; Rollem Fork Surface Mine #2, located about 8.5 miles west of Atenville, West Virginia. Take Route 68 west for 3 miles, turn left on Route 68 / 1 (Francis Creek Road) and drive approximately 6 miles. Just before Frances Creek empties into Kiah Creek a dirt road branches off to the right up a small hill. Site is 1 mile up this dirt road on the right.