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69-706: Wissahickon Creek is a tributary of the Schuylkill River in Montgomery and Philadelphia Counties, Pennsylvania . Wissahickon Creek rises in Montgomery County, runs approximately 23 miles (37 km) passing through and dividing Northwest Philadelphia before emptying into the Schuylkill River at Philadelphia . Its watershed covers about 64 square miles (170 km). Much of the creek now runs through or next to parkland, with

138-673: A talc schist which contains the mineral talc, so soft it can be scratched with a fingernail. In 1694, Johannes Kelpius arrived in Philadelphia with a group of like-minded German Pietists to live in the valley of the Wissahickon Creek. They formed a monastic community and became known as the Hermits or Mystics of the Wissahickon. Kelpius was a musician, writer, and occultist . He frequently meditated (some believe in

207-465: A cave—the Cave of Kelpius 40°01′25″N 75°12′02″W  /  40.023544°N 75.200665°W  / 40.023544; -75.200665 ) along the banks of the Wissahickon and awaited the end of the world, which was expected in 1694. No sign or revelation accompanied that year, but the faithful continued to live in celibacy by the stream, searching the stars and hoping for the end. Kelpius described

276-440: A common building material in the 19th and early 20th centuries. In addition to Wissahickon schist, there are layers of quartzite in the valley. Both schist and quartzite are metamorphic rocks formed from sedimentary deposits of mud and sand that one time were washed from ancient continents into a shallow sea. These sedimentary deposits were over time compressed into shale and sandstone. During long periods of mountain building,

345-585: A fountain sculpture by Alexander Stirling Calder that is located in the center of Logan Circle , also known by its historic name Logan Square , in Philadelphia, contains three large Native American figures that symbolize the area's major streams: the Delaware, the Schuylkill, and the Wissahickon. The young girl leaning on her side against an agitated, water-spouting swan represents the Wissahickon Creek. Tributary A tributary , or an affluent ,

414-522: A literary and artistic movement known as Romanticism. Romantics valued heroism and chivalry in people, and regarded the wild, free, and untamed nature as the "natural" model of true beauty . Philadelphians finally came to value their Wissahickon valley for its wild character. Even when the mills were still operating, there were remote stretches of wild bluffs and overarching trees; now the old mills had become romantic and picturesque, with mossy stone walls suggesting medieval ruins. In 1924, area residents formed

483-574: A lofty tree growing in the sea itself, raised its head above the apparent waters. Except the setting-sun sending his horizontal beams through all the variety of reds and yellows of the branches of the trees in Long Island, and giving, at the same time, a sort of silver cast to the verdure beneath them, I have never seen anything so beautiful as the foggy valley of the Wysihicken. Actress Fanny Kemble , grandmother to novelist Owen Wister , visited

552-400: A new river, to be given its own name, perhaps one already known to the people who live upon its banks. Conversely, explorers approaching a new land from the sea encounter its rivers at their mouths, where they name them on their charts, then, following a river upstream, encounter each tributary as a forking of the stream to the right and to the left, which then appear on their charts as such; or

621-507: A policeman patrolled the span, questioning all pedestrians walking the bridge. Once the stream enters the city of Philadelphia, the creek valley and its deeply wooded gorge form part of the Fairmount Park system in Philadelphia, a jewel of a park and of nature set in the middle of an urban landscape. The park here is a ruggedly beautiful valley for the naturalists, artists, fishermen, bicyclists, equestrians, and hikers who are drawn to

690-494: A private toll road , the Wissahickon Turnpike, linked the entire valley. Long gone were the religious mystics; here instead the mills of Wissahickon Creek made paper, cloth, gunpowder, sawed lumber, milled wheat and corn, and pressed oil from flax. A sizable population worked at the mills and lived in the valley in small villages like Rittenhousetown and Pumpkinville. The nation was becoming an industrial nation, and

759-400: A river or stream that branches off from and flows away from the main stream. Distributaries are most often found in river deltas . Right tributary , or right-bank tributary , and left tributary , or left-bank tributary , describe the orientation of the tributary relative to the flow of the main stem river. These terms are defined from the perspective of looking downstream, that is, facing

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828-465: A rock overlooking the valley to drop balls of yarn which contained messages about British troop movements during the occupation of Philadelphia. This is likely a legend, for other stories speak of a witch named Mom Rinkle who had little to do with the Revolution. There is a Mom Rinker's Rock in the park today. Not until 1826 were the cliffs near the creek's mouth blasted away to provide access to

897-918: A weak tendency to fracture along these layers. In Europe, the term has been more widely applied to any coarse, mica -poor, high-grade metamorphic rock. The British Geological Survey (BGS) and the International Union of Geological Sciences (IUGS) both use gneiss as a broad textural category for medium- to coarse-grained metamorphic rock that shows poorly developed schistosity, with compositional layering over 5 millimeters (0.20 in) thick and tending to split into plates over 1 centimeter (0.39 in) thick. Neither definition depends on composition or origin, though rocks poor in platy minerals are more likely to produce gneissose texture. Gneissose rocks thus are largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Metamorphic rock showing stronger schistosity

966-449: Is a stream or river that flows into a larger stream ( main stem or "parent" ), river, or a lake . A tributary does not flow directly into a sea or ocean . Tributaries, and the main stem river into which they flow, drain the surrounding drainage basin of its surface water and groundwater , leading the water out into an ocean. The Irtysh is a chief tributary of the Ob river and

1035-475: Is a gneiss resulting from metamorphism of granite, which contains characteristic elliptic or lenticular shear-bound grains ( porphyroclasts ), normally feldspar , surrounded by finer grained material. The finer grained material deforms around the more resistant feldspar grains to produce this texture. Migmatite is a gneiss consisting of two or more distinct rock types, one of which has the appearance of an ordinary gneiss (the mesosome ), and another of which has

1104-702: Is a swimming area on the mouth of Cresheim Creek . As the ravine widens into the Cresheim, the waters gather in a basin surrounded on either side by rocky outcroppings before flowing into the Wissahickon Creek. Legend has it that the Native American Lenape tribes used this as a spiritual area, where local author Phyllis Knapp Thomas writes that "...the Good Spirit is claimed to have banished the Evil Spirit into deep, dark waters". Although it

1173-411: Is also the longest tributary river in the world with a length of 4,248 km (2,640 mi). The Madeira River is the largest tributary river by volume in the world with an average discharge of 31,200 m /s (1.1 million cu ft/s). A confluence , where two or more bodies of water meet, usually refers to the joining of tributaries. The opposite to a tributary is a distributary ,

1242-518: Is called gneissic banding. The darker bands have relatively more mafic minerals (those containing more magnesium and iron ). The lighter bands contain relatively more felsic minerals (minerals such as feldspar or quartz , which contain more of the lighter elements, such as aluminium , sodium , and potassium ). The banding is developed at high temperature when the rock is more strongly compressed in one direction than in other directions ( nonhydrostatic stress ). The bands develop perpendicular to

1311-449: Is classified as schist, while metamorphic rock devoid of schistosity is called a granofels . Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, and so forth. Gneiss rocks may also be named after a characteristic component such as garnet gneiss, biotite gneiss, albite gneiss, and so forth. Orthogneiss designates a gneiss derived from an igneous rock , and paragneiss

1380-513: Is not legal due to unsafe levels of pollutants, Devil's pool has become a popular area to swim, lounge, and drink. Unfortunately, Devil's pool often falls victim to litter and vandalism. However, recent efforts to clean the site by the Friends of the Wissahickon have been moderately successful. Another outlook in the park is Mom Rinker's Rock , on a ridge on the eastern side of the Park just north of

1449-517: Is one from a sedimentary rock . Both the BGS and the IUGS use gneissose to describe rocks with the texture of gneiss, though gneissic also remains in common use. For example, a gneissose metagranite or a gneissic metagranite both mean a granite that has been metamorphosed and thereby acquired gneissose texture. The minerals in gneiss are arranged into layers that appear as bands in cross section. This

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1518-533: Is one of fewer than 600 National Natural Landmarks in America. Recently, interest in reintroducing brook trout to the Wissahickon Valley portion of Fairmount park has been growing. Among the earliest references to the valley was by William Cobbett in his book Rural Rides , which takes the form of a series of letters. In one dated 1821 he said, These are the fogs that sweep off the new settlers in

1587-510: Is subjected to extreme temperature and pressure and is composed of alternating layers of sandstone (lighter) and shale (darker), which is metamorphosed into bands of quartzite and mica. Another cause of banding is "metamorphic differentiation", which separates different materials into different layers through chemical reactions, a process not fully understood. Augen gneiss , from the German : Augen [ˈaʊɡən] , meaning "eyes",

1656-502: The Revolutionary War Battle of Germantown , which was fought not too far from the stream. The American General John Armstrong , compelled by the rough terrain to abandon a cannon in the valley, expressed his contempt for the "horrendous hills of the Wissahickon." Later legends tell of American spies taking advantage of the terrain to retrieve information from an informant named Mom Rinker , who allegedly perched atop

1725-625: The American woods. I remember a valley in Pennsylvania, in a part called Wysihicken [ sic ]. In looking from a hill, over this valley, early in the morning, in November, it presented one of the most beautiful sights that my eyes ever beheld. It was a sea bordered with beautifully formed trees of endless variety of colours. As the hills formed the outsides of the sea, some of the trees showed only their tops; and, every now and then,

1794-753: The Chiliast dreams of Petersen. Deep in the woods, where the small river slid Snake-like in shape, the Helmstadt mystic hid, Weird as a wizard over arts forbid. Christopher Morley also portrayed the valley's beauty in his writings. The Wissahickon is mentioned very briefly in A Biography of the Poet, Sidney Lanier by Edwin Mims. Mark Twain mentioned the Wissahickon during the short time he spent in Philadelphia working for The Philadelphia Inquirer : "Unlike New York, I like this Philadelphia amazingly, and

1863-568: The Dunkards and the Ephrata Cloister built a stone house on land previously owned by Dunkards. The structure, used for church retreats, still stands today, and is known as The Monastery , a remaining witness to the Wissahickon's days as an isolated religious refuge. The same steep slopes and gorge that provided an attractive isolation to religious adherents in the 17th and early 18th centuries provided an efficient source of energy for

1932-496: The East Falls-Germantown neighborhoods in Philadelphia. It was completed in 1932 and is 915 feet (279 m) long, 84 feet (26 m) wide, and 185 feet (56 m) above water. It was originally designed to carry a planned extension of a subway into Roxborough, but the subway never reached the bridge. The bridge has been known as a suicide bridge since its opening. Beginning in 1941 for an unknown duration of time

2001-505: The Fly (Frank Amato Publications, 2005) and Small Fry: The Lure of the Little (The Whitefish Press, 2009). Both books describe the Wissahickon Valley and the experience of fly fishing along Wissahickon Creek in the early twenty-first century. Artists have portrayed the stream and its valley: There exists a Currier and Ives Scenery Of The Wissahickon The Swann Memorial Fountain (1924),

2070-671: The Secret History of the Declaration of Independence (1847) may refer not only to the Wissahickon, but to his wife, the former Rose Newman. He wrote: A poem of everlasting beauty and a dream of magnificance – the world-hidden, wood embowered Wissahickon. Depending on one of Lippard's mostly contrived stories, John Greenleaf Whittier wrote about Johannes Kelpius and his followers on the Wissahickon in his 1872 poem Pennsylvania Pilgrim : Or painful Kelpius from his hermit den By Wissahickon, maddest of good men, Dreamed o'er

2139-763: The Walnut Lane Bridge. A tremendous variety of geology is evident along Wissahickon Creek. Three of the geologic regions that the stream passes through are the Newark Basin of Triassic sandstone and shale , the limestone and dolomite of the Chester Valley, and the Wissahickon Formation where the waters of the stream flow into the Schuylkill and eventually the Delaware Rivers. A unique and very distinctive rock of

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2208-518: The Wissahiccon ", in which he wrote: Now the Wissahiccon is of so remarkable a loveliness that, were it flowing in England, it would be the theme of every bard, and the common topic of every tongue, if, indeed, its banks were not parcelled off in lots, at an exorbitant price, as building-sites for the villas of the opulent. Yet it is only within a very few years that any one has more than heard of

2277-431: The Wissahiccon ... the brook is narrow. Its banks are generally, indeed almost universally, precipitous, and consist of high hills, clothed with noble shrubbery near the water, and crowned at a greater elevation, with some of the most magnificent forest trees of America, among which stands conspicuous the liriodendron tulipiferum . The immediate shores, however, are of granite, sharply defined or moss-covered, against which

2346-431: The Wissahickon Creek valley is Wissahickon schist , the predominant bedrock underlying the Philadelphia region, found over a broad swath of southeastern Pennsylvania from Trenton into Delaware and Maryland. This Precambrian to Cambrian stone, first studied in the Wissahickon gorge, has flecks of glittery mica , small garnets , and many-toned shadings of gray, brown, tan, and blue, and is attractive enough to have become

2415-484: The Wissahickon was leading the way. Benjamin Franklin already had noted in his will the high elevation and quality of Wissahickon water, proposing that in some future day the stream be dammed to supply a safe and pure water source for Philadelphia's water supply, and even allocating funds for this purpose. This did not happen, but the quest for pure water affected the Wissahickon's subsequent history. Seeking to prevent

2484-458: The amphibolite or granulite facies. These form most of the exposed rock in Archean cratons . Gneiss domes are common in orogenic belts (regions of mountain formation). They consist of a dome of gneiss intruded by younger granite and migmatite and mantled with sedimentary rock. These have been interpreted as a geologic record of two distinct mountain-forming events, with the first producing

2553-538: The appearance of an intrusive rock such pegmatite , aplite , or granite the ( leucosome ). The rock may also contain a melanosome of mafic rock complementary to the leucosome. Migmatites are often interpreted as rock that has been partially melted, with the leucosome representing the silica-rich melt, the melanosome the residual solid rock left after partial melting, and the mesosome the original rock that has not yet experienced partial melting. Gneisses are characteristic of areas of regional metamorphism that reaches

2622-416: The bottom of the deck in the other direction. These forces stretch out the rock like a plastic , and the original material is spread out into sheets. Per the polar decomposition theorem , the deformation produced by such shearing force is equivalent to rotation of the rock combined with shortening in one direction and extension in another. Some banding is formed from original rock material (protolith) that

2691-412: The cluster of mills at Rittenhousetown , approximately 1.5 mi (2.4 km) up the creek on Paper Mill Run (also known as Monoshone Creek), a small tributary of the Wissahickon. Here William Rittenhouse (grandfather of the astronomer David Rittenhouse ) had in the early 18th century built the first paper mill in America. Gradually this road and other mill access roads were connected, and in 1856

2760-425: The coal fields far upstream beyond Philadelphia's control, but the waters of the Wissahickon had been restored and the beauty of the Wissahickon Valley had been preserved. Most of America became more industrialized, but the Wissahickon valley quietly returned to its original wilderness character. The reason the Wissahickon Valley retained its wilderness character, even after its clean waters were no longer essential to

2829-432: The development of water mills in later years. One miller had by 1690 already constructed a dam, sawmill, gristmill, and house by the narrow shelf of land at the confluence of the Wissahickon with the Schuylkill River, but the rugged terrain of the valley forestalled further development alongside the stream itself. By 1730, however, eight mills had been constructed, and by 1793, twenty-four, along with many dams. Most of America

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2898-402: The direction of greatest compression, also called the shortening direction, as platy minerals are rotated or recrystallized into parallel layers. A common cause of nonhydrodynamic stress is the subjection of the protolith (the original rock material that undergoes metamorphism) to extreme shearing force, a sliding force similar to the pushing of the top of a deck of cards in one direction, and

2967-421: The direction the water current of the main stem is going. In a navigational context, if one were floating on a raft or other vessel in the main stream, this would be the side the tributary enters from as one floats past; alternately, if one were floating down the tributary, the main stream meets it on the opposite bank of the tributary. This information may be used to avoid turbulent water by moving towards

3036-511: The earliest map of this region of Pennsylvania, by Thomas Holme , the stream is called Whitpaine's creek , after one of the original settlers Richard Whitpaine, who owned several large tracts on the creek. Whitpaine was an early land owner in the days of William Penn . Though at first fairly tame, in its last 7 miles (11 km), the Wissahickon stream drops over 100 feet (30 m) in altitude. Its dramatic geography and dense forest attract thousands of walkers, riders, and bikers. Devil's Pool

3105-432: The first-order tributary being typically the least in size. For example, a second-order tributary would be the result of two or more first-order tributaries combining to form the second-order tributary. Another method is to list tributaries from mouth to source, in the form of a tree structure , stored as a tree data structure . Gneiss Gneisses are common in the ancient crust of continental shields . Some of

3174-595: The granite basement and the second deforming and melting this basement to produce the domes. However, some gneiss domes may actually be the cores of metamorphic core complexes , regions of the deep crust brought to the surface and exposed during extension of the Earth's crust . The word gneiss has been used in English since at least 1757. It is borrowed from the German word Gneis , formerly also spelled Gneiss , which

3243-451: The handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has a left tributary which is called Right Fork Steer Creek. These naming conventions are reflective of the circumstances of a particular river's identification and charting: people living along the banks of a river, with a name known to them, may then float down the river in exploration, and each tributary joining it as they pass by appears as

3312-585: The last few miles running through a deep gorge. The beauty of this area attracted the attention of literary personages like Edgar Allan Poe and John Greenleaf Whittier . The gorge area is now part of Wissahickon Valley Park in Philadelphia, and the Wissahickon Valley is known as one of 600 National Natural Landmarks of the United States. The name of the creek comes from the Lenape word wiessahitkonk, for "catfish creek" or "stream of yellowish color". On

3381-521: The middle amphibolite to granulite metamorphic facies . In other words, the rock was metamorphosed at a temperature in excess of 600 °C (1,112 °F) at pressures between about 2 to 24 kbar . Many different varieties of rock can be metamorphosed to gneiss, so geologists are careful to add descriptions of the color and mineral composition to the name of any gneiss, such as garnet-biotite paragneiss or grayish-pink orthogneiss . Continental shields are regions of exposed ancient rock that make up

3450-466: The non-profit group "Friends of the Wissahickon", which still works to maintain the park's unique landscape to this day. Remarks on the Wissahickon in literature by such as Fanny Kemble, Edgar Allan Poe, George Lippard, and others are noted below. However much the stream and its valley were appreciated, it still divided parts of the city. To help overcome this, in 1906 the Walnut Lane Bridge

3519-504: The oldest rocks on Earth are gneisses, such as the Acasta Gneiss . In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding ( gneissic banding ) but poorly developed schistosity and indistinct cleavage . In other words, it is a metamorphic rock composed of mineral grains easily seen with the unaided eye, which form obvious compositional layers, but which has only

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3588-406: The opposite bank before approaching the confluence. An early tributary is a tributary that joins the main stem river closer to its source than its mouth, that is, before the river's midpoint ; a late tributary joins the main stem further downstream, closer to its mouth than to its source, that is, after the midpoint. In the United States, where tributaries sometimes have the same name as

3657-507: The pellucid water lolls in its gentle flow, as the blue waves of the Mediterranean upon the steps of her palaces of marble. The erratic and almost forgotten novelist George Lippard frequently wrote about the Wissahickon, and was even married at sunset on or around May 14, 1847, on a rocky crag called Mom Rinker's Rock , overlooking the stream. One of his books, The Rose of Wissahikon; or, The Fourth of July, 1776. A Romance, Embracing

3726-448: The people in it ... I saw small steamboats, with their signs up—"For Wissahickon and Manayunk 25 cents". Geo. Lippard, in his Legends of Washington and his Generals, has rendered the Wissahickon sacred in my eyes, and I shall make that trip, as well as one to Germantown, soon ..." Ron P. Swegman , a fly fishing angler, artist, and author, wrote extensively about Wissahickon Creek in two illustrated essay collections, Philadelphia on

3795-431: The picturesque mill, the smooth open field, along whose side the river waters, after receiving this child of the mountains into their bosom, wound deep, and bright, and still, the whole radiant with the softest light I ever beheld, formed a most enchanting and serene subject of contemplation. Edgar Allan Poe alluded to Fanny Kemble's writing in his description of a beautiful Wissahickon valley in his 1844 essay " Morning on

3864-666: The river into which they feed, they are called forks . These are typically designated by compass direction. For example, the American River in California receives flow from its North, Middle, and South forks. The Chicago River 's North Branch has the East, West, and Middle Fork; the South Branch has its South Fork, and used to have a West Fork as well (now filled in). Forks are sometimes designated as right or left. Here,

3933-434: The shale and sandstone were slowly transformed into the schist and quartzite found today. In some places, the compression and heat were extreme enough to fuse the schist with emerging igneous rocks into hard-banded gneiss . Other rocks in the valley are layers of igneous pegmatite and remains of granite plutons , embedded crystals within the schist. A few locations close to Devil's Pool and along Bell's Mill Road have

4002-418: The smaller stream designated the little fork, the larger either retaining its name unmodified, or receives the designation big . Tributaries are sometimes listed starting with those nearest to the source of the river and ending with those nearest to the mouth of the river . The Strahler stream order examines the arrangement of tributaries in a hierarchy of first, second, third and higher orders, with

4071-596: The stable cores of continents. The rock exposed in the oldest regions of shields, which is of Archean age (over 2500 million years old), mostly belong to granite-greenstone belts. The greenstone belts contain metavolcanic and metasedimentary rock that has undergone a relatively mild grade of metamorphism, at temperatures of 350–500 °C (662–932 °F) and pressures of 200–500 MPa (2,000–5,000 bar). The greenstone belts are surrounded by high-grade gneiss terrains showing highly deformed low-pressure, high-temperature (over 500 °C (932 °F)) metamorphism to

4140-399: The stream in 1832; her writing awakened a more general interest in the stream and its valley. Her description of the gorge's dramatic end at the stream's confluence with the Schuylkill River and her verse To the Wissahickon both sparked a keen interest in this natural treasure often overlooked by its neighbors. She wrote: The thick, bright, rich-tufted cedars, basking in the warm amber glow,

4209-492: The stream's industrial discharges from affecting the purity of the water of the Schuylkill River, the Fairmount Park Commission took title of much of the land along the Wissahickon in 1869-1870, and continued to expand its holdings in subsequent decades. The mills were razed; the last active mill was demolished in 1884. Several decades later the Schuylkill River itself became seriously polluted by sources in

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4278-432: The streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes a third stream entering between two others is designated the middle fork; or the streams are distinguished by the relative height of one to the other, as one stream descending over a cataract into another becomes the upper fork, and the one it descends into, the lower ; or by relative volume:

4347-635: The two communities. At least two from the original group, Johann Seelig and Konrad Matthaei, continued as hermits along the Wissahickon into the 1740s. Other religious groups were also associated with the Wissahickon: On Christmas Day in 1723 the first congregation of the Church of the Brethren in America – often called Dunkard Brethren – baptized several new members in the stream. Around 1747, an individual with connections to both

4416-458: The type of meditation he used in his Method of Prayer. (See Further Reading below on this book.) Kelpius died in 1708 and the group disbanded some time thereafter. Some members likely gave up on celibacy and married. A few joined the somewhat like-minded religious colony of Ephrata Cloister under Conrad Beissel in Ephrata , Lancaster County , even though no previous connection existed between

4485-543: The water supply of the city of Philadelphia, was the advent of Romanticism and the changing attitudes which this thought engendered about nature. Before the 19th century, nature had seemed a capricious and ambivalent force, at times a dream, but at times a nightmare. Nature, according to orthodox Christian thought, had fallen with man; though the Renaissance brought about both a new view of mankind and nature, this new attitude took time to grow, but it eventually resulted in

4554-497: The water, and the sidewalks of the bridge 120 feet (37 m) above the Wissahickon. In the past, there was an annual parade of horses, riders, and carriage annually in May for Wissahickon Day, a festive Gala popular among Philadelphia's Equestrians and social elites. The Wissahickon Memorial Bridge , also known as Henry Avenue Bridge, is a stone and concrete bridge that carries Henry Avenue over Wissahickon Creek, joining Roxborough and

4623-428: The wooded, steep banks of the stream. Precipitous wooded inclines that rise more than 200 feet (61 m) above the water create a feeling of remoteness and mountain vastness. There are two main and many smaller bridle paths crossing the park's 1,372 acres (5.55 km) along the Wissahickon Creek. Thomas Mill Covered Bridge , the only covered bridge in a major US city, spans the creek in the park. The Wissahickon Valley

4692-470: Was built over the stream, which was the world's largest concrete arch bridge at the time. The bridge joined the Roxborough and Germantown neighborhoods of Philadelphia, formerly separated by the Wissahickon gorge. The bridge is but 480 feet (150 m) long, with a width of 60 feet (18 m), but its center arch spans an impressive 225 feet (69 m), the crown of the arch is 109 feet (33 m) above

4761-441: Was still wilderness, but the Wissahickon Valley was a developing industrial center. There were more than fifty watermills by 1850, though the thickly forested region about the stream still retained the character of a wilderness. Access roads were being constructed into the steep valley, but there was still no road that followed the stream itself. The nature of the rugged terrain can be comprehended in an event that had occurred during

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