This county park is familiar to many passing on the NJ Turnpike for its mass of volcanic bedrock rising 175 feet above sea level. Many forces shaped this rock, from movement of the Wisconsin Glacier 15,000 years ago to blasting and mining in the 20th century. Laurel Hill once housed churches, a hospital, and a prison. It is said to have been the inspiration for Prudential Insurance’s “Piece of the Rock” logo and slogan.
Laurel Hill Brief History
A 61 meter (203 feet) high pipe-like diabase intrusive, which is believed to be an offshoot of the nearby Palisades Sill. Mineralized shales and sandstones, intruded by the diabase, are visible in the north and southwest sections of the property. Minerals were found in veins in both the diabase and metamorphosed sediments. Quarrying took place from the late 1800s to the 1950s, when a section of the land was utilized as a prison (Penetentiary Quarry). In 1962 Hudson County finished closing their facilities on the site, which included the county prison and the insane asylum. The County entered into a 20 year contract with Callanan Industries to level much of the hill. In the 1960's and 70's Gallo Asphalt had 4 asphalt plants, side by side, adjacent to the quarry and supplied paving materials throughout the surrounding urban region. Production ended on schedual in 1982. In the early 2000s, further blasting occurred along the New Jersey Turnpike. Most of the original 184 acre parcel is currently being utilized as a county park. (This site is also known as "Snake Hill.")
Fine- to medium-grained, dark gray to black intrusive igneous rock. Diabase is one of the dark rocks known commercially as "black granite." It is extremely hard and tough and is commonly quarried for crushed stone, under the name "trap." Chemically and mineralogically, diabase closely resembles the volcanic rock basalt, but it is generally somewhat coarser grained.
- Take a picture with yourself and GPS visible on top of Laurel Hill.
- Find a good example of Diabase atop and post a picture.
- Examine a piece of Volcanic Diabase. Why would this rock be useful for paving blocks?
Notes: Requirements 1) and 2) should be posted to the cache page. Requirement 3) should be emailed to the Cache Owner.
|Picture 1: Laurell Hill
||Picture 2: Skyline & Trains
||Picture 3: PolskiKrol & GPS/Diabase