Fossil charcoal in bituminous coal (Pikeville Formation, Middle Pennsylvanian; Rt. 15 roadcut north of Jackson, Kentucky, USA) 1

Fossil charcoal in bituminous coal from the Pennsylvanian of Kentucky, USA. (bedding plane view; ~12.0 cm across at its widest)

 

This is a sample of bituminous coal from a large roadcut north of the town of Jackson, Kentucky. The outcrop has Pennsylvanian-aged cyclothemic sedimentary rocks of the Breathitt Group (formerly the Breathitt Formation). The succession is dominated by interbedded sandstones and shales, with some coal horizons. The latter include bituminous coal and cannel coal (see elsewhere in this photo album).

 

The striated, shiny silvery pieces seen on this coal bedding plane are fossil charcoal (= burned wood fragments). The Pennsylvanian was a time of low carbon dioxide (CO2) and high oxygen (O2) levels in Earth's atmosphere; forest fires were relatively common events. The source of oxygen was abundant photosynthesizing trees in widespread forests. Earth's first global forestation event occurred during the Pennsylvanian. (See: www.jsjgeology.net/Berner-talk.htm). Charcoalized fossil wood can be found in some abundance in Pennsylvanian sedimentary successions. The original wood microstructure is usually well preserved, but the charcoal fragments themselves are quite delicate. A gentle rub with a finger turns these fragments into black powder. At some localities & in some horizons, the fossil charcoal is partially pyritized.

 

Stratigraphy: float from the Pikeville Formation, Breathitt Group, lower Middle Pennsylvanian

 

Locality: Jackson North outcrop - loose piece from coal bed exposed in the wall above the 1st bench on the southern side of a large roadcut on the eastern side of new Rt. 15, just south of the southbound old Rt. 15-new Rt. 15 split, north of the town of Jackson, north-central Breathitt County, eastern Kentucky, USA (~37° 34’ 51” North latitude, ~83° 23’ 09” West longitude)