The Susquehanna River river drops 1,191 feet in the course of its journey from Cooperstown, New York, to the Chesapeake Bay. It has found many changes in the landscape by way of which it flows more than the previous 325 million decades.
These days, the Susquehanna River is deemed one of the oldest rivers in the United States — if not the oldest. The river flows above rocks that are more youthful than by itself — and that is distinctive.
Rewind the earth’s geologic video to at the very least 325 million yrs back. In the vicinity of Baltimore, Maryland, and Wilmington, Delaware, there ended up the Taconic Mountains, formed from an island arc collision some 425 million several years in the past. The Appalachian Mountains did not nonetheless exist. An ocean occupied the space the place that mountain assortment is positioned nowadays. Even though the Taconic Mountains have eroded, the river was flowing in the opposite course of today, developing its early channel.
Rapid ahead to 300 million many years back, and a massive collision between Africa and North The united states transpired to assist in forming the supercontinent Pangaea. This collision is regarded to geologists as the Alleghanian Orogeny, which seriously deformed our crust into a series of folds and damaged parts of crust made up of faults. The Appalachian Mountains were pushed up for the duration of this episode, which lasted about 20 million years. The Appalachian Mountains were being once as significant as the existing-working day Rockies. Now, with the Appalachian Mountains the high issue, the Susquehanna River reversed its training course and flowed in a southeastern way.
For the next 150 million many years, the constant downward erosion of the river minimize into the crust, creating its channel and declaring its real estate.
About 200 million decades in the past, Pangaea was effectively underway to splitting aside into the earth we know nowadays. This series of rifts did not participate in a large purpose in the life of the Susquehanna. The river was flowing via a comparatively flat simple as the crust would both go with Africa or continue to be with North The united states.
Meteor served form bay
Advancing the online video ahead to post Pangaea, severe weathering and erosion labored on the landscape, and the Susquehanna River carried considerably sediment downslope on to a continental shelf of the freshly born North The usa. Some researchers propose that some 4 to 5 miles of the crust were being eradicated from in excess of our heads by these procedures with help by the river.
About 35.5 million decades back, our spot was greeted with an extraterrestrial customer. An asteroid or meteor collided with Earth in what is these days the southern portion of the Chesapeake Bay. Traveling at about 144,000 miles for each hour, the item made a 25-mile vast crater a half mile deep. This event was the initial action in building the Chesapeake Bay. The Chesapeake Bay Influence is a person of the best-preserved craters in the world, though today sediments have slumped into the substantial melancholy.
The final chapter of this tale will involve Pennsylvania’s final geologic celebration recognised as the Ice Age. From at least 770,000 to 17,000 a long time ago, four ice advancements introduced a just one-mile-superior wall of ice into northern and northwestern Pennsylvania. Meltwater from each individual improvement uncovered its way down the Susquehanna River, adding to its erosional price.
Specifically at the close of the Ice Age, the additional meltwater from the glaciers developed intense downcutting of the Susquehanna River, forming significant potholes in the bedrock. It can be shown in which the river at the time flowed about 200 ft larger than its current-working day elevation.
At some point, all over 10,000 to 8,000 a long time back, the Susquehanna River experienced fashioned a 400-foot deep canyon where by it flowed into the Chesapeake Bay. Currently, sedimentation has loaded in the canyon and aided generate what we know of nowadays as the Atlantic Coastal Plain.
Jeri Jones is geologist who lives in York County, Pennsylvania.