More on Stones
Have you ever heard of a person collecting ordinary stones? It sounds strange but my wife, Mary Alice, collects stones (I don’t mean diamonds) from areas that we visit. When back home she finds a home for the stones in the flower gardens and along the driveway. We knew a lady that lived in Monroeton that always talked about her rock garden. We stopped by one day and saw that she had a genuine rock garden, where there were no flowers only stones. In the future, geologists will be surely puzzled when rocks from one part of our country are found many miles away.
However, the transporting of stones is not new. Over 300 years ago, Native Americans transported stones up and down the East Coast. In Pennsylvania, we have a stone known as jasper that the Native Americans mined from pits near the present town of Vera Cruz, which is located south of Allentown. More than 100 jasper pits have been discovered in that area. Jasper is a type of quartz in shades of red, yellow and brown. The Native Americans found this stone ideal for making arrow heads, spear tips and axes.
After reading about jasper, I began to wonder if there is a difference between a rock and a stone. Webster’s dictionary defines a rock as a large outstanding natural mass of stone; a natural mass of one or more minerals, consolidated or loose. Our word rock is believed to go back to the old French word rocque, meaning stone. Our word stone comes from the Germanic word stein, meaning stiffness or solidity and also the source of the Greek word stia, meaning pebble. Webster’s dictionary defines a stone as a detached piece of rock.
Geologists study rocks to learn about the earth’s past. Fossils are found with the remains of the durable parts of a plant or animal that lived on earth millions of years ago. Fossils have also been found with an imprint of a foot of an animal, such as a dinosaur.
Fossils, which are usually found in sedimentary rocks, are a type of rock that makes up three-quarters of the land surface of the earth. Charlie Fox, a retired earth science teacher, is responsible for my interest in looking for and collecting fossils. Fossils are fairly abundant in Bradford County. Here, in our county, we have many stone walls that were erected by early farmers while clearing their fields. Stones from these walls have revealed many trilobites.
Mother Nature has also transported rocks from one area to another.
The Appalachian Mountains that run through Pennsylvania have an interesting history. The Appalachians, which are ancient mountains that were as lofty and mighty as the present Rocky Mountains; however, they have been worn down by wind and water. During what is known as the Permian Period, the Appalachians were born as the earth had a great folding; causing the great basin that covered most of Pennsylvania to be lifted to a great height. However, erosion attacked the mountains, and they soon became a flat featureless plain, which stood only a few scores of feet above sea level.
Then, another force began to operate on the Appalachians. This time, instead of being folded, the area was lifted vertically. The higher the mountains were lifted, the more the streams and rivers gnawed at the rocks.
The Susquehanna and Delaware Rivers cut passes through the mountains known as water gaps. If traveling on Route 15 south from Sunbury to Harrisburg, you are going through a water gap. When looking at the mountains on both sides of the river, you’ll notice that they are the same height. If the river is low, rows of rocks that run from one mountain to the other are visible, allowing us to see how the mountains were eroded by the river. Also visible are the rocks that stand almost vertically, most often seen where the highway department cut through the mountains to build the highway.
The last period to attack the Appalachians was the Pleistocene Epoch (Ice Age). The last two advances of the ice glaciers entered into Northern Pennsylvania, pushing rocks and stones ahead. Each time the glaciers retreated, the melting ice deposited a mantle of rocks that was picked up and deposited hundreds of miles away. Along with many different varieties and sizes of rocks, these glacial deposits also contained clay and sand.
The North Central part of the state, including Bradford County and into Northeastern Pennsylvania, is known as the Allegheny Plateau. This plateau is a highland that has been eroded by streams, which created deep valleys and a hilly topography. This area has many lakes, swamps, peat bogs and extensive deposits of loose sediments. Unlike the rocks in the mountains to our south, the rocks in this area are primarily laying horizontally because these rolling hills were formed by the water of the receding glaciers. Since moving water has a tendency to separate things, gravel banks will produce items of the same size.
On your next venture into the mountains and hills of Pennsylvania, a very interesting story can be seen if you take the time to look closely at the rocks and mountains.