The Paoli-Thorndale Regional Rail Line is unique among the SEPTA Regional Rail Lines in that between Ardmore and Malvern it follows the Schuylkill-Delaware River drainage divide and further west crosses the Schuylkill-Delaware River divide along the Chester Valley south wall. The Paoli-Thorndale Regional Rail Line, which was originally the Pennsylvania Railroad main line and which now also serves as a segment of Amtrak’s Keystone Corridor, originates at 30th Street Station on the Schuylkill River banks and extends westward along the Schuylkill-Delaware River drainage divide to serve Philadelphia’s Main Line suburban communities before gradually descending into the Chester Valley and the East Branch Brandywine Creek drainage basin west of Malvern. At Downingtown the route crosses the East Branch Brandywine Creek, which flows in a south direction from hills to the north across the east-northeast oriented Chester Valley and then into hills to the south. Thorndale at the west end is still in the East Branch Brandywine drainage basin, but is near the East Branch Brandywine Creek-West Branch Brandywine Creek drainage divide, with the West Branch Brandywine Creek also flowing from hills to the north across the Chester Valley and into hills to the south. This guide describes the route as seen from a train traveling west from Philadelphia. While this guide treats the Schuylkill and Delaware Rivers as two separate rivers, readers should be aware that the Schuylkill River flows in a southeast direction to join the southwest oriented Delaware. River at Philadelphia and is a Delaware River tributary.
30th Street Station to Overbrook:
The 30th Street Station is built on the Schuylkill River banks just south of a Schuylkill River turn from flowing in a southeast direction to flowing in a south-southwest direction. East of the Schuylkill River the Philadelphia City Center is built on the Coastal Plain, but west of the Schuylkill the railroad is located in the Piedmont Province. The primary difference between the Coastal Plain and the Piedmont Province is the elevation of the underlying older and well-consolidated bedrock material. Surface materials on the Coastal Plain are generally “young” and poorly consolidated sediments, which overlie older and better-consolidated bedrock materials. In the Piedmont Province older and well-consolidated bedrock materials are found near or at the surface and give many Piedmont Province regions significantly higher elevations than the Coastal Plain elevations. The Schuylkill River surface elevation near 30th Street Station is essentially at sea level and the river is flowing along the Coastal Plain-Piedmont Province boundary. The entire trip west from 30th Street Station to Thorndale will in the Piedmont Province.
Examples of the older and well-consolidated bedrock materials can be seen from an outgoing train shortly after leaving 30th Street Station on the left (west) as the train curves to the north (as the train passes a rail yard for storing SEPTA trains). The modest bedrock exposures along the rail line are metamorphic schist and gneiss of the Wissahickon Formation, which is often considered to be Ordovician in age (although a Precambrian age has also been proposed). Other examples of the bedrock material are exposed in cuts further along the route. After passing the bedrock exposures the outgoing train turns in a northwest direction and climbs almost 200 feet in elevation as it travels through a region where urban development has significantly altered the adjacent landscape until the Overbrook Station is reached. The railroad is built in the valley of what was once a southeast oriented Schuylkill River tributary, although today the stream flows in storm sewer lines under the surface and is not seen until just after leaving Overbrook Station.
Overbrook to Merion:
After leaving Overbrook Station the outgoing train continues to climb in elevation as it travels northward in the valley of a small south oriented stream. The stream can be seen on the right (or east) side of the train before reaching Merion Station and is the stream that eroded the southeast oriented valley through which the train traveled to reach Overbrook Station. The name Overbrook describes the situation precisely. The station and rail line are located over the brook, which flows underneath at that point. At Merion Station the rail line has reached an elevation of almost 250 feet and the hills on either side of the stream valley in which the rail line is located reach elevations greater than 300 feet.
Merion to Narberth:
Continuing beyond Merion Station the outgoing train turns from a north direction to a west direction as it crosses the drainage divide separating the south flowing Merion stream drainage basin from the south oriented drainage basin of the East Branch Indian Creek drainage basin just before reaching Narberth Station (elevation about 260 feet). The East Branch Indian Creek is crossed after leaving Narberth Station and joins the West Branch to form south oriented Indian Creek, which flows to Cobbs Creek, which flows to Darby Creek, which in turn flows to the southwest oriented Delaware River.
Narberth to Wynnewood:
After departing Wynnewood Station the outgoing train crosses south-flowing East Branch Indian Creek headwaters and begins to climb again to reach Wynnewood Station. Wynnewood Park is located on the north (right) side of the train after crossing East Indian Creek. Wynnewood Station has an elevation of approximately 300 feet and the ridge to the north (right side of train) rises to more than 370 feet and is the divide between the Schuylkill and the Delaware River drainage basins.
Wynnewood to Ardmore:
After leaving the Wynnewood Station the outgoing train curves so as to travel in a northwest direction and continues to gradually climb to an elevation slightly higher than 350 feet as it finally reaches the divide between the Schuylkill River and the Delaware River drainage basins at Ardmore. While not easily seen from the train the area just north of the Ardmore Station (right side of outgoing train) drains to Mill Creek, which flows to the Schuylkill River and the area to the southwest (left side) drains to Cobbs Creek which flows to Darby Creek, which in turn flows to the Delaware River. This drainage divide has been carved in the metamorphic schist and gneiss bedrock and became an important transportation route because it avoided the problem of crossing the numerous stream valleys carved on either side of the divide. The drainage divide crest does have its ups and downs, but those ups and downs were much easier for the railroad builders to deal with than trying to bridge the streams valleys found on either side of the divide.
Ardmore to Haverford:
The gradual climb along the drainage divide continues after leaving Ardmore Station to an elevation of approximately 380 feet at Haverford Station. Trees and buildings hide the slopes on either side of the railroad, but the train is traveling along the drainage divide between the Delaware River to the southwest (left side of outgoing train) and the Schuylkill River to the northeast (right side). If you if get off the train and start walking to the northeast you will soon descend into the valleys of Mill Creek tributaries with the water eventually reaching the Schuylkill River. If you walk to southwest you will find the Haverford College campus with the Cobbs Creek headwaters on the southwest side.
Haverford to Bryn Mawr:
The drainage divide elevation continues to climb as the outgoing train travels along it from the Haverford Station to the Bryn Mawr Station, which has an elevation of approximately 430 feet. The area to the northeast of the train (right side of the outgoing train) drains to Mill Creek, which flows to the Schuylkill River. The area to the southwest does not slope as rapidly as it is the drainage divide between the south-southeast flowing Cobbs Creek headwaters and south-southwest flowing Meadowbrook Run, which flows to south-southeast oriented Darby Creek. Bryn Mawr is the Welsh word for “great hill” and the Bryn Mawr Station is located near a local high point.
Bryn Mawr to Rosemont:
As previously noted the drainage divide between the Delaware River and the Schuylkill River drainage basins has its ups and downs and one of the major downs is crossed after the outgoing train leaves Bryn Mawr Station. The train will descend into the notch or wind gap, which is crossed on a fill, and much lower elevations are seen on either side of the train. The Rosemont Station is reached just before crossing the deepest part of the notch. The valley to southwest (left side of the outgoing train) is the headwaters of Meadowbrook Run, which flows in a south-southwest direction to join south-southeast oriented Darby Creek (a Delaware River tributary). Drainage in the valley to the northeast (right side) flows to east and north-northeast oriented Mill Creek (a Schuylkill River tributary). The notch and the south-southwest oriented Meadowbrook Run valley mark what is probably a fault line between the lower Paleozoic age Wissahickon Formation schist to the southeast and Precambrian age gneiss to the northwest. Fault movement probably created a zone of easier to erode bedrock, which accounts for the wind gap and Meadowbrook Run locations. However, the wind gap and the Meadowbrook Run valley were both eroded by running water that probably came from the northeast prior to headward erosion of the east oriented Mill Creek valley, which was prior to headward erosion of the southeast oriented Schuylkill River valley.
Rosemont to Villa Nova:
Immediately after departing Rosemont Station an outgoing train is still traveling on the embankment across the deep notch, but soon begins to climb again as it heads in a northwest direction to reach the Villa Nova Station (elevation approximately 430 feet). At the Villa Nova Station, which is located on the Villa Nova University campus, the rail line leaves the Delaware-Schuylkill divide and enters the head of the east, southeast, and north-northeast oriented Mill Creek drainage basin (Schuylkill River tributary) although the head of south oriented Valley Run (a Meadowbrook Run tributary with water flowing to Darby Creek and then the Delaware River) is just a short distance to the south.
Villa Nova to Radnor:
From the Villa Nova Station the outgoing train climbs slightly as it travels to a shallow cut across the drainage divide from the Mill Creek headwaters (with water flowing to the Schuylkill River) and enters the Hardings Run drainage basin (with water flowing to Ithan Creek, then to Darby Creek, and next to the Delaware River). The track elevation in the cut is between 440 and 450 feet. The Schuylkill-Delaware River divide elevation in this area is generally between 400 and 450 feet with some isolated points reaching an elevation of slightly more than 480 feet. Shortly after passing through the shallow cut the outgoing train crosses Hardings Run (a very small stream at this point) and then quickly passes over Interstate 476 and the third rail electrified Norristown High Speed Rail Line as it descends slightly and curves to the west to reach Radnor Station. The Norristown High Speed Rail, which follows the Cobbs Creek valley headward crosses the Delaware-Schuylkill River divide in a cut into the floor of a shallow notch north of where the Paoli-Thorndale crosses it and then descends into the Gulph Creek valley (with water flowing to the Schuylkill River) and eventually ends in Norristown after crossing the Schuylkill River. Radnor Station is on the Delaware River side of the drainage divide with water flowing to south oriented Ithan Creek and has an elevation of approximately 450 feet.
Radnor to St. Davids:
Leaving Radnor Station an outgoing train is traveling in a west direction and until after leaving the St. Davids Station is on the Delaware River (Ithan-Darby Creek) side of the Delaware-Schuylkill River divide. The drainage divide is located only a short distance to the north (right side of outgoing train) and ranges from 20 to 50 feet higher than the rail line, which maintains an elevation of approximately 400 feet.
St Davids to Wayne:
During the short trip from the St. Davids Station to the Wayne Station (elevation approximately 400 feet) an outgoing train crosses from the Delaware River (Ithan-Darby Creek) side of the drainage divide to the Schuylkill River side of the divide where it enters the Gulph Creek drainage basin. Gulph Creek is located in the valley seen north of the train at the Wayne Station and is flowing in an east direction. Further downstream Gulph Creek flows in a northeast direction before turning in a north-northwest direction to flow through a deep water gap used by the Norristown High Speed Rail Line to cross a 200-foot high ridge. After flowing through the water gap Gulph Creek flows in an east-northeast direction to join the southeast oriented Schuylkill River.
Wayne to Strafford:
Between the Wayne Station and the Strafford Station an outgoing train is following the Gulph Creek valley headward to where Gulph Creek originates today. The rail line has an elevation of approximately 400 feet and the hill to south reaches 450 feet in elevation while the hills to the north (which form the Gulph Creek-Chester Valley drainage divide) rise to more than 500 feet. In other words, the Gulph Creek headwaters are draining an area on the Delaware River side of the highest ridge located between the Delaware and Schuylkill River drainage basins. The hills north of the Strafford Station rise to more 550 feet and separate the Gulph Creek headwaters from headwaters of north oriented streams that flow into the Chester Valley with water eventually reaching the Schuylkill River (remember Gulph Creek is also a Schuylkill River tributary). South of the Strafford Station is the head of the south oriented Little Darby Creek valley, which drains to Darby Creek and then to the Delaware River. The east oriented Gulph Creek valley and the south oriented Little Darby Creek valley meet in the Strafford area and form a continuous through valley bounded by hills ranging from 50 to 100 feet higher than the through valley floor. The through valley also links the east oriented Gulph Creek valley with the south oriented Darby Creek headwaters valley, which are seen after leaving Strafford Station. This through valley provides evidence that water once flowed across the present day Delaware-Schuylkill River divide. Based on evidence from a larger region the water was probably moving in a west direction along the present day east oriented Gulph Creek alignment prior to erosion of the Gulph Creek and Schuylkill River valleys and was flowing to what at that time was the actively eroding Darby Creek valley. Headward erosion of the deep southeast oriented Schuylkill River valley captured the west flowing water and caused a flow reversal that resulted in headward erosion of the Gulph Creek valley. Headward erosion of these deep valleys probably required massive and prolonged flood flow, which suggests the water probably came from a melting ice sheet.
Strafford to Devon:
After leaving Strafford Station the outgoing train continues west on the floor of the shallow through valley linking the east oriented Gulph Creek headwaters valley (draining to the Schuylkill River) with the south oriented Darby Creek headwaters (draining to the Delaware River). At Devon Station the rail line is located at the head of a southwest and south oriented Darby Creek tributary valley and has an elevation slightly higher than 450 feet. Hills on the north side of the outgoing train reach an elevation of 550 feet, although the train has crossed the Schuylkill River-Delaware River divide by traveling along the floor of the through valley, which at its highest point has an elevation of about 460 feet.
Devon to Berwyn:
Upon leaving Devon Station the outgoing train climbs in elevation as it crosses the heads of south oriented valleys draining to Darby Creek (and then the Delaware River) until it reaches an elevation greater than 500 feet at the Berwyn Station, which is also located on the Delaware-Schuylkill River divide. South of the railroad is the head of the south oriented Darby Creek valley while north of the Berwyn Station is the head of the north oriented Trout Creek headwaters valley. Trout Creek flows in a north direction onto the floor of the Chester Valley and then turns in a northeast direction to flow on the Chester Valley floor to eventually reach the southeast oriented Schuylkill River. On its way to the Schuylkill River Trout Creek is joined by other north oriented streams that originated in the hills seen north of the railroad tracks between Strafford and Berwyn.
Berwyn to Daylesford:
Between Berwyn and Daylesford the outgoing train is traveling along the Delaware-Schuylkill River divide at an elevation slightly greater than 500 feet. Daylesford Station is located at the head of a south (and then east) oriented Darby Creek tributary (left or south side of outgoing train) and at the head of a north oriented stream that flows onto the Chester Valley floor where it joins northeast oriented Valley Creek, which after flowing on and across the Chester Valley turns to flow in a north direction through a 250-foot deep water gap cut across the Chester Valley north wall to reach the Schuylkill River. From Daylesford to Frazer (a SEPTA rail yard and maintenance facility location between Malvern and Exton) drainage on the north (or right) side of the railroad is to Valley Creek, which should not be confused with the Valley Creek further west, which drains much of the Chester Valley segment between Frazier and Downingtown to the East Branch Brandywine Creek.
Daylesford to Paoli:
For a short distance on its trip between Daylesford and Paoli the outgoing train is traveling on the Schuylkill River side of the drainage divide and there is a low hill to the south. But at Paoli the rail line is again on the Delaware-Schuylkill River divide with the head of the Crum Creek valley just south of the Paoli Station and the head of a north oriented stream flowing into the Chester Valley and then to Little Valley Creek, which flows to Valley Creek just north of the Paoli Station. The Paoli Station is located at the west end of a cut through a low hill that has an elevation slightly greater than 550 feet.
Paoli to Malvern:
Between Paoli and Malvern the rail line continues to be located along the Delaware-Schuylkill River drainage divide, and to maintain an elevation of close to 550 feet above sea level. North of the rail line (right side of an outgoing train) are heads of north oriented valleys draining into the Chester Valley with water flowing to Little Valley Creek and then Valley Creek and eventually reaching the Schuylkill River. South of the rail line (left side) are heads of valleys draining to Crum Creek, which flows directly to the Delaware River. Darby Creek, Crum Creek, Ridley Creek, and Chester Creek all flow from this region to independently join the southwest oriented Delaware River in the same region near Chester, PA. Just before reaching the Malvern Station the rail line leaves the drainage divide and begins its gradual decent into the Chester Valley. The Malvern Station is located at the head of a north oriented draining to northeast oriented Little Valley Creek, which flows to northeast and north oriented Valley Creek, which in turn flows to the Schuylkill River.
Malvern to Exton:
West of Malvern Station the rail line is located on the Schuylkill River side of the Delaware-Schuylkill divide and views of the Chester Valley (right side of the outgoing train) are possible when the trees permit. Chester Valley floor elevations in this region are generally lower than 400 feet and at deeper locations are less than 300 feet. The ridge on the north side of the Chester Valley has a slightly higher elevation than the ridge along the south side and at selected points is as much as 700 feet high. The rail line is descending very gradually from its 550-foot elevation in the Paoli area and is slightly below 500 feet at Frazer where a SEPTA rail yard and maintenance facility can be seen on the north (right) side of the train (Frazer is not a SEPTA passenger stop). Between Malvern and Frazer the rail line crosses the heads of several north oriented valleys the first few of which drain to northeast oriented Little Valley Creek, which flows to northeast and north oriented Valley Creek, which in turn flows to Schuylkill River. In the Frazer area the rail line crosses several north oriented valleys draining to northeast and north oriented Valley Creek including the north oriented Valley Creek headwaters valley.
Just before passing under a divided highway (Route 202) the outgoing train crosses another north oriented valley at Glenloch (not a SEPTA passenger stop) and has again entered the Delaware River drainage basin, this time by entering the Brandywine Creek drainage basin. The north oriented valley at Glenloch (just before going under route 202) is the headwaters of west-southwest oriented south oriented Valley Creek, which south of Downingtown joins south oriented East Branch Brandywine Creek, with Brandywine Creek flowing directly to the southwest oriented Delaware River. In other words between Frazer and Glenloch the outgoing train crosses in rapid succession the north oriented headwaters of two completely different Valley Creeks, the first Valley Creek once in the Chester Valley turns to the northeast and flows gradually across the Chester Valley before turning in a north direction to flow through a deep water gap to join the Schuylkill River, the second Valley Creek once in the Chester Valley turns in a west-southwest direction to flow on the Chester Valley floor before turning in a south direction to flow through a deep water gap to reach south oriented East Branch Brandywine Creek. In the short distance between these two independent Valley Creeks is the Schuylkill-Delaware River drainage divide, which is no longer located on the high ridge the train followed from Ardmore to Malvern, but which now extends down the Chester Valley wall as it separates the two independent Valley Creek drainage basins. From Glenloch to Exton the rail line continues its gradual descent along the side of Chester Valley south wall and at Exton Station has reached an elevation that is slightly less than 400 feet.
Exton to Whitford:
The north oriented valley crossed immediately after leaving Exton Station drains to the west-southwest and south oriented Valley Creek, which flows to the East Branch Brandywine Creek. Between Exton and Whitford the rail line continues to descend along the side of the Chester Valley south wall. An abandoned rail line blocks views of the Chester Valley on this stretch, but that changes after leaving Whitford Station. The south wall ridge is composed of erosion resistant metamorphic rocks (e.g. schist and gneiss) while the Chester Valley floor to the north is underlain by less erosion resistant carbonate rocks (e.g. limestone and dolomite). The north oriented valley crossed just before reaching the Whitford Station also drains to west-southwest and south oriented Valley Creek (which flows to East Branch Brandywine Creek). Whitford Station has an elevation of approximately 340 feet and is approximately 200 feet lower than at Paoli.
Whitford to Downingtown:
Upon leaving Whitford Station the outgoing train travels under the abandoned rail line bridge and the abandoned rail line is now on the left side of the outgoing train permitting good views of the Chester Valley to the north (right side). The SEPTA and Amtrak rail line is still gradually descending as it continues along the side of Chester Valley south wall. Elevations in the Chester Valley area drained by west-southwest oriented Valley Creek to the north are less than 300 feet and Valley Creek is flowing at an elevation of approximately 250 feet as it turns in a south direction to flow in a narrow valley across the 500-foot high Chester Valley south wall to reach south oriented East Branch Brandywine Creek. Chester Valley carbonate rocks have been mined or quarried extensively and evidence for such mining operations is seen in the Chester Valley to the north at approximately the same point where Valley Creek turns to flow in a south direction across the Chester Valley south wall, which is located where the rail line curves in a northwest direction so as to enter the Chester Valley. Unfortunately the railroad embankment for the active SEPTA and Amtrak rail line and the higher elevation abandoned rail line to the south completely hides views of the Valley Creek water gap to the south, although the valley can be located by a road passing under the rail line (visible on the north side only). Once on the Chester Valley floor the rail line curves in a west-southwest and then west direction as it enters Dowingtown and crosses the East Branch Brandywine Creek just before reaching Dowingtown Station. Dowingtown Station has an elevation of approximately 260 feet, which is almost 300 feet lower than at Paoli. The East Branch Brandywine Creek originates in the hills north of the Chester Valley and flows in approximately a south direction into and across the Chester Valley and then enters a 300-foot deep and narrow valley carved into the hills south of the Chester Valley.
Downingtown to Thorndale:
After leaving Downingtown Station the outgoing SEPTA train continues to Thorndale by traveling along the Chester Valley floor south margin and there are views of the Chester Valley to the north. This Chester Valley segment is drained by east-northeast oriented Valley Run, which joins south oriented East Branch Brandywine Creek at Downingtown. North oriented valleys crossed between Downingtown and Thorndale all drain to Valley Run. To reach the Thorndale Station the outgoing train travels headward along the south side of the Valley Run valley and in doing so gains elevation. Thorndale Station has an elevation of approximately 330 feet and is as far west as the SEPTA trains go. However Amtrak continues further west along the Chester Valley floor to the drainage divide between the East Branch Brandywine Creek drainage basin and the West Branch Brandywine Creek drainage basin and then to Coatesville where the West Branch Brandywine Creek flows from the hills to the north across the Chester Valley floor and into a narrow valley carved into the Chester Valley south wall. The Chester Valley is a classic example of a through valley drained today by more than one stream. It was eroded headward from west to east as headward erosion of progressively deeper south valleys oriented valleys captured the west-southwest oriented flood flow and caused reversals of flow on the east-northeast ends of the beheaded flood flow routes. Erosion of the Chester Valley occurred during the same massive and prolonged southwest oriented floods that were responsible for eroding most southeast Pennsylvania stream and river valleys.