Site: PGHBW 4-3

A View of the Point from Grandview Avenue, Pittsburgh, PA


Latitude:                             40° 26' 23"N

Longitude:                          80° 01' 18"W

Quadrangle:                       Pittsburgh West 7 1/2'

Age:

Formation(s):

Purpose:                            This site provides one of the best views of the Historic and geologically significant Point of Pittsburgh.

Access and Parking:

Park on nearest side street (Sweetbrier St.) and walk across Grandview Avenue to overlook. Parking for motor coach with prior permission from local businesses (Monterey Bay Fish Grotto) or residents. Recommended for all age groups.



Mass Transit Directions:

(Make sure you get an up-to-date PAT Transit schedule:

From Oakland, take any bus to downtown Pittsburgh. Then either walk across Smithfield Street Bridge or take T to Station Square. The take Duquesne incline or Monongahela Incline to Grandview Avenue. Walk to site. Return.

Driving Directions:

From the Cathedral of Learning, Drive 0.7 mi. west on Fifth Avenue. Make a Left on Craft Av. Go 0.1 mi., then make a right onto Blvd. of Allies, go 1.6 mi. then follow signs to Liberty Bridge and into the Liberty Tunnel. BEFORE entering tunnel, make a right onto McArdle Roadway and follow up to Grandview Avenue. Go 0.5 miles along Grandview Avenue and park as directed above.

See map and figures.

What you will see:

“The Point” refers to the location where the Monongahela River and the Allegheny River merge to create the Ohio River in the area that is now downtown Pittsburgh. With the coming of European settlers in the mid 1700s, The Point became a strategic location in protecting the frontier, first for the French with Fort Duquesne and later for the British with Fort Mercer and Fort Pitt. During the 1800s and early 1900s, the Point area became an industrial complex and the center of the American steel industry. Today, the Point is the focus of the transition of Pittsburgh from an industrial giant to that of a financial and cultural center.

As you look out from this vantage point, you will see the relative flat Southside, Downtown, North Side, and, to the west, Brunot Island. The flat areas are all underlain by glacial sands and gravels and later river gravels. The flat area abruptly terminate against the adjacent hills such as Mt. Washington (on which you are now standing). Imagine, if you will, that during the Pleistocene glacial events, meltwater from glaciers just 50 km to the north flowed into the Pittsburgh area and possibly covered much of the lowlands you see with shifting, braided rivers and occasional meltwater lakes.

Geologic History:

George Washington wrote in his Journal (1754):

 “As I got down before the Canoe, I spent some Time in viewing the Rivers, and the Land in the Fork; which I think extremely well situated for a Fort, as it has the absolute Command of both Rivers. The Land at the Point is 20 to 25 Feet above the common surface of the Water; and a considerable Bottom of flat, well timbered Land all around it, very convenient for Building: The Rivers are each a Quarter of a Mile, or more across, and run here at very near right Angles: Aligany N.E. and Monongahela S.E. The former of these two is very rapid and swift running Water; The other deep and still, without any perceptible Fall.”

 The Point is located at the confluence of two major Rivers, the Allegheny, which drains much of northwestern Pennsylvania, and the Monongahela which drains much of southwestern Pennsylvania and northern West Virginia. These two major rivers meet to form the Ohio River, which then flows, first northwestward, then southwestward toward the Mississippi River. However, as pointed by Leverett (1934), Wagner and others (1970), and Harper (1997, http://www.dcnr.state.pa.us/topogeo/pub/v28n3-4.pdf) the configuration of the rivers has not always been as we see it today. The Allegheny River has changed markedly since the period of continental glaciation that covered much of northern North America (below). (http://www.watershedatlas.org/watershed/fs_create.html). Similarly, the Monongahela River has changes its course many times over the history of the river. To view a map of the ancient courses of the river see http://www.watershedatlas.org/watershed/fs_meander.html.

Figure from Harper (1997). Map showing the present-day configuration of the major rivers in Western Pennsylvania and the maximum extent of Ice advance during the Wisconsin glaciation (~15,000 years ago). To examine the landforms or physiographic province of the Allegheny watershed click to http://www.watershedatlas.org/allegheny/fs_landforms0.html, and for the Monongahela watershed http://www.watershedatlas.org/fs_explrmon.html.

Figure from Harper (1997). Map showing the configuration of the rivers in Western Pennsylvania before the Ice Age. Note that the Upper Allegheny and Middle Allegheny Rivers flowed northward toward the St. Lawrence River, as did the Ohio River. The presence of the ice sheets caused the rivers to change to their modern courses.

Today, in Pittsburgh, the rivers flow over an accumulation of glacial sediments (sand and gravel) that were deposited during the last Ice Age when glaciers advanced as far south as Slippery Rock, PA Figure above). During that time, glacial meltwater significantly added to the volume of water flowing in the Allegheny river. The river valleys were consequently widened and their floors covered with a thick blanket of debris that had been washed out of the ice. Since that time, the rivers have deposited a layer of fluvial (river derived) sediments as floodplain deposits.

These deposits make up downtown Pittsburgh, the Southside, and much of the North Side. Beneath the layers of glacial and fluvial sediment is Pennsylvanian age (~280 – 300 million year old) bedrock consisting of shale, sandstone, limestone, and coal that were originally deposited in ancient coal swamps, freshwater lakes, and occasional marine (ocean) transgressions. The Point area in underlain by the Conemaugh Group or ‘the upper barren measures’ (referring to the general lack of minable coals in the unit). To the east and south, the higher elevations (generally above 900’) are underlain by the Monongahela Group or ‘the upper productive measures’ (referring to the productive Pittsburgh Coal horizon that separate the two groups).

Figure from Harper (1997). Development of the Allegheny and Monongahela River valleys over the past 1 million years, as shown in cross section. Sections A-C show how the rivers eroded downward as the land rebounded after being ‘weighed down’ with glacial ice. Note that in the area that is now Downtown Pittsburgh is underlain by a blanket of glacial sand and gravel then a layer of more recent nonglacial river deposits such as sand silt and clay.

Pittsburgh Then and Now

Some of the earliest descriptions and contemporary drawings of the point area are from the time of Fort Duquesne which was built on the site in 1754. The figure below shows a drawing done during or soon after the fort was built, presumably by Capitan François Le Mercier, who was the engineer in charge of construction (Stotz, 1985). This plan shows a sharp point of land at the Point with erosional bluffs along the river banks. The river banks are not straight, but have a concave erosional pattern. A later drawing by Joseph Gaspard Chaussegros de Léry (below), King Louis XV’s chief engineer in Canada also shows the bluffs, but the river banks appear straighter than in the earlier map. In 1758, J.C. Pleydell, an engineer with the British army made a plan of the fort that shows the morphology of the Point quite well, especially the steep bluffs along the banks. The height of the bluffs is not known precisely, but Stotz (1985) mentions that they were “15 to 20 feet high and were rutted by erosion, exposing glacial clay, sand and gravel that composed the soil.” John McKinney, an English prisoner at Fort Duquesne described the area immediately east of the fort in these words:

 “There is no bogs or morasses near the fort, but good dry ground, which is cleared for some distance from the fort, and the stumps cut close to the ground; a little without musket shot of the fort in the fork is a thick wood of some bigness full of large timber” (Stotz, 1985).  

Although occasionally flooded, the Point was not a marsh, but high dry land. From these drawings and descriptions, Stotz (1985) prepared an artist’s rendering of the Point during Fort Duquesne time. Using these descriptions and maps as well as later maps, Laurent (1980) provided an artist’s rendering of an even earlier, pre-Fort Duquesne view of the Point.  

Plan of Fort Duquesne made by Capitan François Le Mercier (circa 1754-1755). From Stotz (1985). Note the irregular shoreline and the steep bluffs. During this time period, the ‘Allegheny River’ was still referred to as Rivere D’Ohio ou Belle Rivere (Ohio River or Beautiful River).

Map of Fort Duquesne and environs made by Léry in 1755. From Stotz (1985). Note the very accurate and careful measurements of the river widths

In 1819, Riddle and Murray (1819) described the Pittsburgh area as follows: 

“The ground upon which Pittsburgh is built is nearly level and bout forty feet (on an average) higher than the surface of the river at low water… Besides the tableland, which constitutes the principle part of the city, there were, in the year 1780, two parallel flats upon the Allegheny shore, each about 300 yards broad, extending half a mile from the Pittsburgh Point. The lowest of these, that is, the one next to the river, has been entirely washed away, together with a considerable portion of the second. At the same time (1780) there stood near the shore of the outer flat a row of handsome buildings which were erected for the reception of Indian traders. One portion of the row had been demolished as it was supposed to stand in an inconvenient position with regard to the fort, and the other part was presently precipitated into the Allegheny.”

By taking information from the old pre-1800 maps of the Point, two overlay reconstructions have been made to visualize where the river shorelines, islands, and ponds were in colonial times with respect to modern-day Pittsburgh. The figure to the right below shows a close-up of the point and the location of the point as it was in the late 1700s. Note how small the point was then compared to today. If we look at the entire downtown Pittsburgh region, we see the location of the Islands on the North side with respect to the present position of the Carnegie Science Center and the former location of Three Rivers Stadium. Also, note the locations of Hogg Pond and other ponds in downtown Pittsburgh as well as the island in the Monongahela River.  Compare the 1795 and 1815 maps with the recent air photo:

              

1795                        1815                             Today

Islands

 There are many islands (http://watershedatlas.org/lowerallegheny/fs_natsys3.html) throughout the Allegheny, Monongahela and Ohio Rivers in the Pittsburgh area. One of the primary functions of rivers is to transport sediments from the headwaters to lower elevations. The source of the sediments is usually erosion of soil and weathered rock fragments, but may also be glacially-deposited sediments as in the case of the Allegheny River. During periods of high velocity flow, especially during flooding event, the river can transport large amounts of sediment. As floodwaters recede and velocities drop, the sediment is deposited. Islands begin with the slow accumulation of sand and gravel deposited over years of flooding.  Eventually, these accumulations break the surface of the stream or river to form an island. Along with the deposition of sand and gravel, silt and clay accumulates among the interstices, the pores spaces between gravel, and becomes the soil medium that supports the growth of subaquatic vegetation, grasses, shrubs, and eventually trees. The plant species found on islands are well adapted to full sun, moist to wet soils, and seasonal flooding. Sycamore trees and alder shrubs are common woody plants found on islands.

Once an island is established, erosion begins to work on both the upstream and downstream tips of the island. If the island is predominantly gravel, it will last a long time. If the composition of the island is mainly sand and silt, however, one can readily witness the erosion of its upstream and downstream tips over a fairly short time. Islands are ephemeral, instream landscape features; they grow with deposition, and wash away with erosion. Islands in the three rivers come in many sizes. Some are ten acres or less, while others, like Neville Island, can be hundreds of acres.

 Islands Here and Islands Gone

 Kilbuck Island 

On all early maps and drawing of Pittsburgh, an island, or in some cases a series of islands are shown in the vicinity of the present-day Carnegie Science Center and Heinz Field.  Although not shown on any earlier maps, the island across the Allegheny from the Point was first referred to by Léry in 1755. He described on his drawing “…an island which is a peninsula when the water is at medium…” A single large island is shown on Elais Meyer’s 1761 map. A sand bar, presumably covered at high water, connects it to the north shore much as described by Léry. The 1795 map (above) shows two islands and a small peninsula, the larger island is called Smokey Island. The Plan of Pittsburgh from a 1796 engraving by Tardieu L’Aine does not show any islands, but the accuracy of the north shore area depiction is in question as there appears to be a stream shown in the area of the islands that is hidden by the figure caption. The 1815 Darby map and the 1825-1826 the map of the area shows three islands (Kilbuck, Low, and a small unnamed island) and a ‘sand bar at low water.’ The 1825-1826 map appears to be a derivation of the 1815 map because the shapes of the islands are nearly the same. A good contemporary view of Smokey island is shown in an 1817 sketch drawn by Mrs. E. C. Gibson, member of the Philadelphia Bar while on her wedding journey (Laurent, 1980). By 1850, a map of Allegheny City by Day and Cramer (From Cowin, 1985) shows that Smokey or Kilbuck Island is again now just a peninsula off of the North Side. 

By the early 1900s, the backwaters behind the islands was filled in to make room for industrial development on the North Side.

The Island in the Mon 

The 1795 (above) and 1815 (above) maps both show a large island in the middle of the Monongahela river The large sand bar was used as buckwheat fields in the late 1700s. Significantly, the island so well depicted on the 1795 and 1815 maps is not present on any earlier maps (Figures II-18 and II-23 in Stotz (1985)), Elias Meyer’s 1761 map nor on the first sketch of Pittsburgh drawn in 1794 by Louis Brantz, a Philadelphia merchant). This suggests that a major flooding event between 1794 – 1795 deposited the material that was to become the island. The island then persisted to at least 1815. A sketch of Pittsburgh in 1817 does not show the island. However, the 1825-1826 map by H. H. Bernhard, Duke of Saxe-Weimar Eisenach shows the island as a “sand bar dry at low water,” but again, this just may be a copy of the 1805 map.

 Wainwrights Island

 Wainwrights Island was located in the Allegheny River adjacent to what is now Lawrenceville. http://www.clpgh.org/exhibit/neighborhoods/lawrenceville/lawb.html. In the words of Fleming (1915) “Wainwright's Island [has] long since wasted away, [but] it was on this island that [Christopher] Gist and [George] Washington landed after their perilous voyage across the Allegheny, full of heavy floating ice, on an improvised raft in 1753, while returning from their mission to the French commander, St. Pierre, at LeBoef, now Waterford, Pa. Washington records in his journal December 27, 1753, that they built the raft with one poor hatchet and finished after sunset, putting a whole day in the work. The next day they launched it and getting aboard, pushed it off. He [Washington] continues:

“Before we were half way over we were jammed in the ice and in such a manner that we expected every moment our raft to sink and ourselves to perish. I put out my setting pole to try and stop the raft that the ice might pass by, when the rapidity of the stream threw it with so much violence against the pole that it jerked me out into 10 feet of water, but fortunately, I saved myself by catching hold of one of the raft logs.
Notwithstanding all our efforts, we could not get to either shore, but were obliged as we were near an island to quit our raft and make for it.“

The two put in a miserable night, Gist having his fingers and toes frozen, but the channel between the island and bank froze so hard they had no difficulty in crossing in the morning and then made their way to the cabin of John Frazier, the English trader on the Monongahela, at the mouth of Turtle Creek.”

Most likely the narrow backwater between Wainwrights Island and Lawrenceville was filled in the late 1800s to make more land for development. However, it is still shown on an 1863 map showing the “Defenses of Pittsburgh” (Cowin, 1985, page 317).

Today, in the vicinity of Pittsburgh, there are three islands in the Ohio River (Brunot Island, Davis Island, and Neville Island) and six in the Allegheny River (Herrs Island, Sixmile Isalnd [located six miles from the point], Sycamore Island, Ninemile Isalnd, Twelvemile Island, and Fourteenmile Island). There are no islands in the Monongahela River near Pittsburgh. The large number of islands in the Allegheny is a reflection of the large amount of glacially-derived sediment that was moved by the river. For an interesting coverage of the Ohio River Islands see Ferrick-Roman (2001).

Anthropogenic changes in the Point area:

As Pittsburgh became a center for river commerce during the Industrial Revolution, the fickle nature of river flow continued to plague riverboat captains. Even into the late 1800s, the Monongahela Wharf (Figures 20 and 21) area along the south side of the city was commonly an area used for boats to wait out periods of low flow before starting or continuing their journey.

 n      To remedy this problem, locks and dams were constructed to maintain pool level and river flow.

n      In 1837, The Monongahela Navigation Company, chartered by the Commonwealth of Pennsylvania, began building a series of seven locks and dams from Pittsburgh to the West Virginia state line.

n      Lock and Dam No. 1 was located one mile from the Smithfield Street Bridge along the Monongahela River

n      Lock and Dam No. 2 was located at Braddock’s Upper Ripple, above the mouth of Turtle Creek, approximately 10 miles from No. 1, also along the Monongahela River

n      To minimize river bank erosion, seawalls have been constructed along much of the urban river shoreline.

n      Many physiographical and topographical features described by travelers and early settlers, and depicted in early maps have been covered with fill during periods of urbanization and redevelopment.

Click on the thumbnails below for pictures:

A view of the Point and City of Pittsburgh. The point is an accumulation of non-glacial river gravels.
This photo is a pan to the northeast of the city, showing the North Side.
A further pan to the north of the city. The flat area is underlain by glacial sands and gravels.
This photo looking west along the Ohio River toward Brunot Island.

Fossils:

No fossils found here.

References:

Alberts, R. C., 1980, The Shaping of the Point: University of Pittsburgh Press, Pittsburgh, PA, 247 p.

Cowin, V. L., 1985, Pittsburgh Archeological Resources and National Register Survey, Ph.D. Dissertation, University of Pittsburgh, Pittsburgh, PA, 507 p.

Ferrick-Roman, K., July 29, 2001, Islands of the Ohio, The Times Sunday, The Times/BeaverNewspapers, Inc., Beaver, PA.

George T. Fleming, "Stories of Lawrenceville," Pittsburgh Gazette Times, 24 January 1915.

Harper, J., 1997, Of Ice and Waters Flowing: The Formation of Pittsburgh’s Three Rivers: Pennsylvania Geology, v. 28, p. 2-8.

Hunter, W. A, 1960, Forts on the Pennsylvania Frontier, 1753-1758: Pennsylvania Historical and Museum Commission.

Leverett, F., 1934, Glacial deposits outside the Wisconsin terminal moraine in Pennsylvania: Pennsylvania Geological Survey, 4th Series, General Geology Report 7, 123 p.

Lorent, S., 1980, Pittsburgh, The Story of an American City: Third edition, Authors Edition, Inc., Lenox, MA, 670 p.

Kussart, S., 1938, The Allegheny River. Pittsburgh: Allegheny River Improvemetn Association, 1938.

Reece, F. R. ed., 1944, Colonel Eyre’s Journal of His Trip from New York to Pittsburgh, 1762: Western Pennsylvania Historical Magazine, 27, March-June, p. 37-50.

Riddle, J. M., and Murray, M. M., 1819, The Pittsburgh Directory, Butler and Lambdin, Pittsburgh.

Roberts, P. ed., 1996, Points in Time: Building a Life in Western Pennsylvania: Historical Society of Western Pennsylvania, Pittsburgh, PA, 124 p.

Stotz, C. M., 1985, Outposts of the War for Empire, The French and English in Western Pennsylvania: Their Armies, Their Forts, Their People, 1749-1764: Historical Society of Western Pennsylvania, Pittsburgh, PA, 203 p.

Schafer, J., and Sanja, M., 1992, The Allegheny River: Watershed of the Nation, The Pennsylvania State University Press, Unversity Park, Pennsylvania, 304 p.

Stryker, R., and Seidenberg, M. eds., 1959, A Pittsburgh Album, 1758-1958, Two Hundred Years of Memories in Pictures and Text: Pittsburgh Post-Gazette, Pittsburgh, PA, 95 p.

Wagner, W. R., Craft, J. L., Heyman, L., and Harper, J. A., 1975, Greater Pittsburgh Region Geologic Map and Cross Sections, Pennsylvania Geological Survey Map 42.

Wagner, W. R., Heyman, L., Gray, R. E., and others, 1970, Geology of Pittsburgh Area: Pennsylvania Geological Survey, 4th Series, General Geology Report 59, 145 p.

Click here for  an image of the County Geologic Map (1880)

 

 

 

 

 

 

 

 

 

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