What Lies Beneath?
AL ZAGOFSKY/SPECIAL TO THE TIMES NEWS Geologist Brian Oram points to a layer of anthracite coal in an exposed section along Rt. 309 at the Borough of Luzerne. The coal as with all the layers, were once horizontal. The collision of the continental plates created the uplifting.
You don't have to be a geologist to notice that northeastern Pennsylvania is a special place. It has mountains, plateaus, valleys, gorges and coal mines-with many variations of often rugged and picturesque landscapes.
To find out why northeast Pa. is the way it is, it wouldn't hurt to consult with a professional geologist like Brian Oram. Oram is an administrator in the Environmental Engineering and Earth Sciences, and the director of the Center for Environmental Water Testing Laboratory at Wilkes University in Wilkes-Barre.
Oram drove to a section north of Wilkes-Barre where a rock mountainside had been blasted open to construct Rt. 309 near the borough of Luzerne. Here, layers of rock lay exposed one upon another.
To our left, he pointed out the upper layer of rock, the Llewellyn Formation-named after the community of Llewellyn in Schuylkill County.
The Llewellyn layer is mostly gray with buff, brown and black areas formed of sandstone, siltstone, shale, conglomerate and anthracite coal in repetitive sequences.
To our right, he pointed out the younger rocks of the reddish gray Mauch Chunk formation-named after the former town that merged into the borough of Jim Thorpe.
Looking at the section through the mountain reveals that the rocks are arranged in layers. Today, these layers either rise or fall - rarely are they flat, but these layers were originally flat.
The layers were formed by the action of water and decaying plant life leaving behind layers of sediments. When conditions changed, the layers of sediments changed. Thus, the sediments, which formed sedimentary rock, contain a record of the history of the Earth.
If this process continued undisturbed, a section through the Earth would reveal what Oram calls "layer cake geology."
"In most places, the geology ranges from layer cake geology where the formations were deposited in near horizontal beds that now tend to tip or plunge in one direction," he noted, "to more exciting places where we have a series of anticlines and synclines where rocks have been folded."
Oram describes these features as frowns and smiley faces. The frowns-anticlines, where rocks folded downward from a crest, and the smiley faces-synclines, where the rocks slope upward forming a trough, are characteristic of the rock formations that lie beneath Northeastern Pennsylvania.
A coal bed can be seen to be in a layer between upturned rock layers. At a point where the layers change direction, coal can be observed accumulating in a pocket.
Oram used a sheet of paper to demonstrate how the layers had folded. Holding the paper flat, he pushed the two ends together and the paper buckled and became wavy.
He explained that after the sedimentary layers formed, the drifting of the continents caused a collision of plates below what is now the northeastern U.S. The Continental Collision, much like the squeezing of the paper, caused portions of the land to rise into ridges or mountains and other areas to be pushed below forming valleys.
Through erosion and the movement of glaciers, the upper rock formations were scraped away. "The coal was protected in synclines as the glaciers advanced," Oram noted. "When the glacier retreated, we had valleys where coal formations were exposed on the side slopes of the valley and as we worked our way into the core of the valley, we found deeper and larger deposits."
In Northeastern Pennsylvania, coal can be found exposed at the surface, and large amounts of are coal within 600 feet of the surface.
Coal was formed millions of years ago at a time when Pennsylvania was further south and much warmer, with a climate similar to the Caribbean. The land was swampy. As time passed, its decaying plants became peat, and then turned to coal.
When the period of mountain building began, the horizontal layers of coal bent into large folds and under heat and pressure, and over time, transformed into anthracite. The mountain building was followed by weathering and glaciers.