Creeky West Mt. Airy


by Burt Froom

West Mt. Airy:  Yesterday and Today

March, 2013 (Article 6)

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In my February, 2013 article about the valleys of the Wissahickon Creek, I left the proto-Wissahickon flowing placidly past the escarpment wall (now about 350 feet high) of the Huntingdon Valley-Cream Valley Fault to an outlet on the Schuylkill River in Andorra. How, then, did the very different scene of today’s rushing Wissahickon Creek in its present towering canyon come about? The Wissahickon Creek had a partner! Surprisingly, it was the Monoshone Creek that arises in in West Mt. Airy!  Both streams were born about 100 million years ago, Dr. James Alcock, retired professor of geoscience at Penn State Abington, says, and were influenced by the fault. The Monoshone flowed from its steep valley (where upper Lincoln Drive now is) to the present mouth of the Wissahickon on the Schuylkill River. It eroded the gentler and longer side of the fault block and began to cut a gorge behind itself in a process that geologists call “headward erosion.”

Headward erosion is the geological process by which the rock wall upslope from the stream’s head is loosened and weakened by the action of water, from springs, tributary streams and heavy rainfall, so that the stream grows longer behind the flow. Headward erosion may not seem obviously or intuitively true, because we think that a stream’s power is mostly downward. But headward erosion is a powerful shaper of many landscapes during millions of years..



Sketch by Dr. James Alcock of conjectured channel created by the proto-Monoshone Creek in the escarpment of the Huntingdon Valley-Cream Valley Fault, by the process of headward erosion, through which the present Wissahickon Creek flows in the gorge begun by the Monoshone Creek.

Here is how science views this process: Short tributaries of the ancient Schuylkill River, flowing west to east transversely across the gentler slope of the fault’s block back and growing by headward erosion. Scientists posit that one stream eroded into the valleys of several other streams and captured their water. This stream would have flowed east into the proto-Monoshone about where the Wissahickon and Monoshone Creeks meet today, at the beginning of Forbidden Drive.  At the same time, this stream, during millions of years of headward erosion, was getting closer to the northwest side of the fault scarp ridge. Its erosion cut a channel and valley to a depth that would have put it below the valley of the proto-Wissahickon flowing from the north on the other side of the scarp.

Eventually, the proto-Monoshone Creek eroded through the scarp and captured the waters of the larger Wissahickon Creek, perhaps less than 10 million years ago. (It is the stream that erodes more actively that is said to do the capturing.) So the Wissahickon Creek vacated its valley to the west and entered its new home that the proto-Monoshone had begun to erode for it! The two creeks now ran together and changed direction to flow south. With the added volume of water now available and the steeper fall in the Wissahickon Canyon, the process of erosion must now have more vigorous to sculpt the cliffs and chasms of the valley today

The Monoshone Creek today is about 2.6 miles long, from its highest point near Allen’s Lane and Germantown Avenue to its confluence with the Wissahickon Creek, and the creek bed has a drop in elevation of about 325 feet in that distance, according to my informal measurement. The Monoshone watershed might be 5.5 square miles. It may have been faster than the Wissahickon, but not as forceful as a generator of power. Its name,”Monoshone,” is thought to be a word of obscure origin and unknown meaning. However, there is a town in the Rhineland-Palatinate state of western Germany named “Monsheim,” now united with the town of Cresheim, which was the source of early settlers in West Mt. Airy. Some people believe that Monoshone is an early corruption of “Monsheim.” This seems a believable proposal to me.

The Monoshone Creek (also called Paper Mill Run), is first mentioned in history when William Rittenhouse leased land on the lower Monoshone and built America’s first paper mill there in 1690.  In 1700 (or 1701), a sudden powerful storm and flash flood destroyed the new stone paper mill in Rittenhouse Town. This was America’s first manufacturing complex. William Penn, the Proprietor of Pennsylvania colony, happened to be visiting then, and he encouraged settlers to contribute to the re-building the mill. The Monoshone was powerful and could be dangerous.

During the 19th century, textile mills, powered by water, were operating along the upper Monoshone Creek valley to produce blankets for American soldiers during the War of 1812.  This mill was replaced by 1845 by the steam-powered Glen Echo carpet and fabric mills, located at Carpenter Lane on the Monoshone, owned by the McCallum brothers, William and Andrew, of Scotland. Eventually, there were 350 workers there and Mt. Airy was a leading industrial site, fueled, presumably, by wood or coal, surely polluting the Monoshone Creek. This mill closed in 1898 after it moved to Wayne Junction in lower Germantown where there were now electricity and railroad transportation to obtain raw materials and market its products. Soon the Monoshone Creek was channeled into pipes when Lincoln Drive was built over it, and West Mt. Airy became mainly residential, its industrial past mostly forgotten.


West Mt. Airy in 1861, from the Mt. Airy section of Philadelphia vicinity map, showing upper Monoshone Creek watershed (and Cresheim Creek) in blue, with houses, buildings and industrial sites (stylized square marks), but with owners’ names removed for clarity. Note much vacant land near the Monoshone. Click the map to download the pdf for a larger image.

The question should be asked, how carefully and responsibly is our generation of Philadelphia residents treating our creeks and their tributary streams, now after more than three hundred years of human residence here? The answer is not as agreeable as we might wish.

The Wissahickon has been called a “creek in crisis” (Chestnut Hill Local, April 5, 2012). In recent years, the Monoshone Creek has been in the news because community groups have pursued the condition of stormwater flowing through the buried pipes that discharge polluted water into the Wissahickon downstream. The Philadelphia Water Department ( has recently agreed to conduct quarterly testing of our stormwater in West Mt. Airy. PWD has found human sewage material in water flowing past Rittenhouse Town and high levels of fecal coliform bacteria. The Monoshone has been declared to be severely polluted. There is concern about contaminated Monoshone water affecting our drinking water from the Queen Lane water treatment plant in the Schuylkill River. The city calls our water, after treatment, “high quality drinking water.”

The third creek in West Mt. Airy is the Cresheim Creek, to our north. This is a stream, flowing in its narrow ravine, about 2.7 miles, from its source at nearly Cheltenham Avenue between Ivy Hill Road and East Mermaid Lane to its mouth at Devil’s Pool and Wissahickon Creek. From its source, Cresheim Creek descends 365 feet to the Wissahickon.This drop provided power for numerous mills built here. Before the later 19th century, it was fed by tributaries from the Chestnut Hill where Winston Road and upper Lincoln Drive are now. (The Wissahickon Creek drops only 100 feet in its last eight miles!)

Many millions of years ago, when the Huntingdon Valley-Cream Valley Fault began to lift up its  escarpment, as I discussed earlier, the present Cresheim Creek valley would eventually have been lifted up to a level between the tops of Chestnut Hill and Mount Airy. That might mean that there was 117 feet of mostly schist stone on top of the intersection of Germantown Avenue and Cresheim Creek, perhaps a mile long. The creek and its tributaries must have eroded out this entire valley of the fault block since perhaps 100 million ago. The creek did an impressive excavation job!

When the first German settlers came here, starting in 1683, they recognized the power in that strong stream. So they built mills on Cresheim Creek as on the Wissahickon and the Monoshone. Garrett Rittenhouse (1674-1742), second son of the founder of the Rittenhouse paper mill, operated a grist (corn meal) mill on Cresheim Creek. Thomas Livezey (1723-1790) also operated a water mill on the creek. The map of 1861 shows at least four mill ponds, three mills, three factories (carpet and cotton), a weaver, and 25 or more buildings (homes, mills and factories) from Germantown Avenue to the Wissahickon Creek. This was not a secluded park as it may look today through a car’s windshield. It was then an industrial corridor, employing many workers. The creek would have been polluted with manufacturing wastes. To the east of Germantown Avenue, where the stream ran slower, there were apparently farms, and large estates and mansions of the wealthy, close to the creek.

Today, there is talk of creating the “Cresheim Trail,” a walking and bicycling path, along Cresheim Creek on the abandoned Pennsylvania Railroad right of way (now owned by PECO) that was a spur from the Allen Lane station to the Fort Washington station on the Chestnut Hill West passenger train, from about 1903 to 1961. The railroad trestle bridge, that auto traffic drives under on Germantown Avenue at Cresheim Valley Drive, remains from those days. A large community group is working together to develop this scheme, the Cresheim Valley Rail-Trail project ( It would join trails to connect Philadelphia, Cheltenham and Springfield townships, Flourtown and Fort Washington State Park. This is a bold and visionary project.for Cresheim Creek valley, which has no walking trails..

As I reflect on these last three Yesterday and Today column articles, I confess that I was unaware of the dramatic origins of our Wissahickon schist, and I did not know how the gorge of the Wissahickon Creek was formed, and about the fault: the ancient fracture of Earth’s foundations, which has lifted up Chestnut Hill and Mt. Airy. We have pondered together the awesome geological processes that shaped our hills and stream valleys during the slow, astounding movements of Earth’s colliding continents. And maybe most amazing of all to me is the deep time, the hundreds of millions of years, that all of this took to happen. Rebecca Solnit, the San Francisco author, gives us words to capture the majestic drama we have been attempting to describe: “Landscape’s most crucial condition is considered space, but its deepest dimension is time.” And all of this magnificence is but a short walk away!