Returning to Red Clay Creek, Delaware
Photo credit: J. R. Blackwell
The first day of October brought me back to ride the rails again of the Wilmington and Western Railroad. On several occasions, I have boarded the train, pulled by the magnificent steam locomotive, the American 98, black, formidable and puffing grey steam out from its chimney. The train followed the Red Clay Creek, a mostly shallow winding stream through woodlands and fields. I photographed several Civil War reenactments along the creek. Now I looked forward to returning for another journey through the Delaware countryside, this time on a geological expedition.
This would be my first outing with the Delaware Mineralogical Society, joining folks who know a great deal of information about rocks, of which I have almost no knowledge, although I have always picked up a souvenir rock during my travels.
I have an affinity with rocks. Now I was about to get some education on the subject.
Building a Railroad through the Rocks
In 1872 the Wilmington & Western Railroad began service to bring goods and passengers among the mills along the creek. Building the line had many challenges including cutting through significant rock outcroppings. According to an article in the Delaware Public Media,
They didn’t really understand geology back then, and Delaware’s got a lot of rock and it’s the foothills of the Appalachians. So their construction costs skyrocketed. Robert Elwood
Not knowing about rocks can cost money!
Robert authored Special 50th Anniversary Historic Timeline: the Wilmington & Western’s Half-Century of Operation and reported that “two massive rock outcrops would require extensive black powder blasting to cut through.” p. 3. One outcropping at Cuba Hill consisted of blue granite; at Wooddale, the rock was more massive but softer. A powder keg exploded at Wooddale, and three workers died as a result. Even opening a powder keg with a sharp tool could cause a barrel to explode. The names of these workers seem to be lost to history, but their involuntary sacrifice noted in Robert’s timeline.
Subduction Leads to Orogeny . . . Really?
Delaware Geologic Survey scientist William “Sandy” Schenck, presented an introductory lesson to the geologic history of the land beneath our feet. The process is best described in this quote from the Geological History of the Delaware Piedmont,
It is surprising to find that although the Delaware Piedmont has passed through the whole series of tectonic events that formed the Appalachians, the mineralogy and structures preserved in Delaware were formed by the early event that occurred between 470 and 440 million years ago, called the Taconic orogeny. This event was triggered by the formation of a subduction zone off the coast of the ancient North American continent that slid oceanic crust on the ancient North American plate beneath oceanic crust on the overriding plate, produced magma, and fueled an arc-shaped chain of volcanoes.
The expression does make a quirky bumper sticker, if you’re into geological humor.
We boarded the 1929 railcar, “The Paul Revere,” to view and understand the rock landscape as it exists now.
If you like the sound of the train, here’s a video as we left the station.
Southeast of Greenbank Station
At our first stop, Sandy pointed out the metamorphosed igneous rocks jutting out along the track. We could see the fractures cause by expansion that crisscrossed along the formation. The third photograph in this series is a close up of the “bright eyes” feldspar surrounding black grains of magnetite, formed by the two tectonic plates colliding.
Studying the Cliffs
The Paul Revere headed back through the Greenback Station, letting us off at several different locations, allowing us to walk through the cliffs on either side of the tracks. It was amazing to imagine the labor necessary in 1870 to carve out a narrow space for the train to pass through what looked like impenetrable rocks. These metamorphosed rocks were originally sedimentary, now layered and jagged.
“To change in appearance or form, especially strangely or grotesquely; transform.”
Changes in land formations certainly would seem to qualify.