The coordinates will lead you to 2 of the several quarries visible from the path (there is another fine example behind the John Prahl house across the road from Parking Coords, but not required).
As Africa and Europe split from North America forming the Atlantic Ocean, sedimentation in the down-dropped Newark rift basins of Mesozoic (occurring between 230 and 65 million years ago ) eastern North America followed a three-part sequence.
As Mountains eroded from the Allegheny orogeny (300 to 250 million BP) the first part formed the Stockton Formation, when basins first dropped, they were small and there was more than enough sediment eroded to keep the basins full. At this stage the area was crossed by rivers. Sand, gravel and silt were the predominate sediments.
Eventually as the basins deepened and border faults lengthened the valleys became wider and longer and sedimentation could not keep up with the down-dropping. And deep lakes formed in the basins, this marked the start of the next geological formation in the area, the Lockatong formation. The Stockton formation shifts to the Lockatong near Raven Rock to the north.
The Stockton formation was famous for the sandstone of its brownstone quarries. A short walk to the north along the Delaware and Raritan Canal Sate Park leads to views of several quarries.
Here at GZ is a fine outcropping in a former quarries (largely overgrown now.) The quarry lies uncomfortably on Precambrian and lower Paleozoic rocks of Piedmont uplands from which the quartz sands (and feldspar) here were derived to form the sediments.
Besides “brownstone” also common here is a fine-grained micaesous sandstone, which is extensively borrowed by a crayfish-like crustacean called scoyenia.
The canal here and railroad (your not standing on a canal tow path but the old Belvidere Delaware Railroad bed) were used for transport. Many fine buildings in the area such as Nassau Hall in Princeton were built from this stone during the 19th into the 20th century. Look at some of the building as you walk here, note their foundations were made from brownstone, a common use.
Brownstone despite the use of a cheaper substitute for granite and marble came to epitomize luxury.
Brownstone was quarried most efficiently where the rock was regularly layered in large beds obliquely cut by fractures. The channeling and wedging method was done by hand, channels on 3 sides were first cut then wedges places in the channels to split the rocks into desired sizes. Steam-powered Machines were used in later years. The rock needed to be stored and “dried out” before use.
Blasting was also used, but made more waste and rubble and some was used as cellar walls. Which brings us to some local history:
Philadelphia, May 17.1888 (New York times)-The most terrific explosion ever known in New-Jersey took place this morning near Stockton, Hunterdon County, N.J. Three hundred cans of blasting powder and 250 dynamite cartridges exploded and killed one man, injured six others, demolished a dozen buildings, and wrecked the town of Stockton, on the Belvidere division of the Pennsylvania Railroad, 19 miles from Tranton and 34 miles from this city. The forman went into the powder magazine at 7:25 o’clock and told Assistant Foreman Peter Hoffman that he was going to get a can of fine powder, and that he would have to move the cans of coarse powder in order to get at the fine powder, which was on the bottom.
Two minutes later there was a great cloud of white smoke, a belch of fire 50 feet high, and a noise like a hundred thunderstorms. The powder magazine, which was 12 feet square and 10 feet high, was shattered into toothpicks. Foreman’s body was blown into a thousand pieces. A hole 10 feet deep and 12 feet square was all that was to be seen where the magazine had stood. Fifty cartloads of dirt and rocks went up with the little building. At the same time a dozen buildings within a quarter of a mile were demolished. A barn north of the magazine was blown out of sight and the hay and debris went up in a blaze that only lasted a few minutes. The quarry blacksmith’s shop, 100 yards away, was torn to splinters, and nothing was left to mark the spot except two anvils and a bellows.
A mile from the quarry lies the little town of Stockton, where the 700 inhabitants live in about 100 pretty houses. All but about a dozen houses were damaged. Some of the houses were left without windows, doors, or shutters. On the main street some of the houses were so badly wrecked that the people moved their furniture out into the streets, boarded up their houses, and took refuge with their neighbors. When the explosion came women and children, some of the half naked, ran through the streets shrieking and wringing their hands. One hundred and forty men were working in the quarry. Most of them are married and live in Stockton. The women, thinking every man in the quarry had been killed, ran up the town to the scene of the explosion, expecting to find husbands, fathers, or sons blown to atoms. Thousands of broken dished were thrown in piles in the middle of the street. Across the Delaware, in Bucks County, Penn., nearly opposite the quarry, nearly a mile away is the little village of Centre Bridge. Half a dozen houses were left without any window panes. The force of the explosion was felt all over Bucks County. Houses in New-Brunswick, N.J., 36 miles away, were rocked by the explosion.
If you go the Catholic Cemetery you'll see the same date on numerous stones.
To claim this Earthcache email your answers to the following though geochacing.com:
1. There is a brownstone wall between you and the quarry. Brownstone is a freestone (brownstone and similar sandstones were known as “freestone” because of properties allowing them to be worked freely in every direction, rather than in one direction along a “grain”) Many brownstones were “ashalar” which simply means that they have the quality to allow the production of a smooth even surface by the tooling and rubbing down of the surface. Feel the stones, In your own words if the wall stones are “ashlar” , what characteristics would make them good candidates for “ashlar” treatment.
2. How long ago was the rock here formed give or take a few million years?
3. Are there any evidence of ancient life here here?
4. Where did the sandstone come from?
5. Extra credit (optional), walking further north can you spot any other quarries across the road (hey it's a nice walk)?
A photo is not required, but we like photos, make us happy.
References:
Roadside Geolgy of New Jersey - David P Harper
PERMIT: DNR20160529001 DATE: 5/29/19