|This index map shows the spatial relation of Lancaster County in southern Pennsylvania to the US East Coast, specifically, the two important estuaries:
Lancaster lies in the top left corner and Lancaster Country borders on the Susquehanna River, the main source of the Chesapeake Bay.
At the end of the last Glacial Age, the Susquehanna was the main passage way of the melting northern icecap, which is still visible from its straight lower course with "hanging" tributaries and numerous giant potholes.
The "Fall-line" separates the Appalachian mountain remnants characterized in PA by rocks of almost all ages from the younger sedimentary wedge of mainly shallow marine sediments which are some 7,000 feet thick along the Delaware shore.
This afforded the early settlers a rich source of almost free water power, which was harnassed by numerous water mills.
To enhance and regulate the flow of water, many small dams were constructed. This impeded the passage of such anadromous fish as the shad to move upstream and inland to spawn, thus ending a rich fishery. Furthermore, each of the reservoirs created collected thick deposits of sediments after deforestation' Recently, these dams were demolished (e.g. Rock Hill dam before and after), which allowed not only the return of the shad but also the bayward movement of the so-called "legacy-sediments" (A-B-C) and associated toxic substances and nutrients.
In the 1800's, a series of navigation canals and a railroad provided the means of transportation (export) of coal, lumber, ores and agricultural products.
In the 1900's, the Susquehanna became the scene of the largest concentration of hydro-electric dams in the World, including the infamous Three Mile Island Nuclear Power Plant.
This sketchmap shows the positions of :
"SW BRIDGE" replaced by a more modern ,but far less
spectacular bridge in the 1950's
Paul, Lexa and Parker ("GPS")
at 118 South Duke Street, northward across the river.
Interestingly, on the title deed,
it was originally located on "Slackwater Road" as well . . .
just north of the steel bridge
crossing at the lower end of the map
Some photos I took on Slackwater walks are shown here.