Overview of the geology of the U.S. state of New Jersey
New Jersey
is a very geologically and geographically diverse region in the United States' Middle Atlantic region, offering variety from the
Appalachian Mountains
and the
Highlands
in the state's northwest, to the Atlantic Coastal Plain region that encompasses both the
Pine Barrens
and the
Jersey Shore
. The state's geological features have impacted the course of settlement, development, commerce and industry over the past four centuries.
New Jersey has four distinct
physiographic provinces
. They are: (listed from the south to the north) the
Atlantic Coastal Plain
Province, the
Piedmont
Province, the
Highlands
Province, and the
Ridge and Valley
Province.
Coastal Plain
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The largest province in the state encompasses the southeast part of the state below the fall zone from
Trenton
to
Carteret
. It contains a large wedge of unconsolidated sediments that have been deposited since the
Cretaceous
Period. These sediments continue off-shore as far as the
continental shelf
edge in the
Atlantic Ocean
. Topography is relatively flat with a few hills of erosion resistant sediments containing gravel or iron-sedimented sands.
[1]
The province is divided further into three subprovinces. One is the Lowland section, which comprises flat, frequently inundated areas of tidal
marshes
,
back bays
, and
barrier islands
. This section generally follows the coastline,
Delaware Bay
, and
Delaware River
. The intermediate upland section comprises raised areas inland and is best suited for farming and other agriculture. The sands of the coastal plain have been mined for
foundry
sand and sand used for glass making. Finally, the upland section is home to the
New Jersey Pine Barrens
and
Fort Dix
.
Glauconite
is commonly found in this section, especially around
Freehold Township, New Jersey
.
[2]
Piedmont
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A majority of the rocks in this province are a part of the
Newark Supergroup
. They include the
Passaic Formation
, the
Lockatong Formation
, the
Stockton Formation
, and the
igneous
rocks
basalt
and
diabase
. In New Jersey, more basalt flows are evident with several named formations including the
Hook Mountain Basalt
, the
Preakness Basalt
, and the
Orange Mountain Basalt
. Diabase is prominently displayed along the
Hudson River
in the
Palisades Sill
. These rocks were deposited during the rifting of
Pangea
during the
Triassic
and
Jurassic
Periods. Much of the northern segment of this region was glaciated and the resultant shaping help to form New York and Newark harbors.
A small portion of the
Pennsylvania
Piedmont Highlands called the
Trenton Prong
extends into New Jersey through Trenton and are mostly
Ediacaran
and
Cambrian
aged rocks, that includes the
Wissahickon Formation
. The
Manhattan schist
exists in New Jersey, largely below New York harbor and in the vicinity of
Bayonne
and
Jersey City
.
[2]
Highlands
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The Highland Province consists of the remnants of a billion year old mountain range that stretched from Newfoundland to Mexico on the edge of the North American continent and was created in the
Grenville Orogeny
.
To the east of the Kittatinny Valley is the Highland province. A narrow fault of Hardyston Quartzite separates the Kittatinny Valley from the Highlands. Igneous and metamorphic rock from the Late Precambrian and Early Paleozoic era, make up the Highlands. Kittatinny and Franklin formation, along with Hardyston Quartzite are in the Highlands. The New Jersey Highlands geology is complicated due to complex patterns of folds, faults and intrusions.
The Highland Province has the Wawayanda Mountains which has an elevation of 1448 at two peaks; Sparta Mountain, elevation 1232: Pochuck Mountain, elevation 1194, north of Lake Pochung; Hamburg Mountain, elevation 1495 east of Lake Wildwood.
This section contains some the oldest rocks in New Jersey and is largely a mix of
Pre-Cambrian
granites
and
gneisses
and lower
Paleozoic
clastic
and
carbonate
rocks.
[2]
The harder granites and gneisses produce steep sided hills and mountains since they are relatively resistant to
erosion
. There are two small
klippes
in the southern part of this province, the Jutland klippe south of
Musconetcong Mountain
and the Peapack klippe in southern
Morris County
.
There are numerous active and abandoned mines in this area because of its rich mineral wealth. Iron, zinc, and marble were all important minerals mined from the New Jersey Highlands.
Franklinite
is a mineral first described at
Sterling Hill Mine
.
Green Pond Mountain in Northern
Passaic County
and into western
Morris County
is a slice of Lower
Cambrian
to Middle
Devonian
rocks that are collected in a half
graben
and are detached from the
Valley and Ridge
sequence. These rocks have always been described separately from the rocks in the Valley and Ridge, but have been cross-correlated to those rocks.
Ridge and Valley
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The smallest province in the state, it is confined to the northwest corner of the state. The
Kittatinny Valley
is a part of the
Great Appalachian Valley
and contain some of the oldest rocks of the province known as the Matinsburg shale created during the Ordovician period. At the edge of this valley is the Kittatinny Ridge which is from 1500 feet to 1800 feet. The ridge goes in a northeast?southwest axis. Beyond this ridge, there are series of rolling hills and small ridges underlain by
Silurian
and
Devonian
aged rocks.
The Kittatinny Ridge was created about four hundred million years ago when a small continent that was long and thin collided with proto North America. The strike caused folding and faulting which cause the Silurian Shawnagunk conglomerate which is made mostly of quartz, to rise out of a shallow sea. The heat from pressure caused the quartz to bend, and silica melted the quartz
granules
together along with other stone. Millions of years of erosion from rain, wind, snow, ice shaped the mountain and valley to its present configuration. The Wisconsin glacier which started to form around 21,000 BC and started to melt in 13,000 BC left boulder fields, end moraines and a terminal moraine which starts north of Belvidere and goes east to just south of Great Meadow and continues east to just north of Budd Lake and continues east to Denviile where it goes southeast toward Morristown and goes around the south end of Great Swamp.
The
Delaware River
is deflected by ridges and travels generally southwest, along the
strike
of the upturned beds of shale
sedimentary rock
. The Delaware flows in a
riverbed
of
glacial
till
in the Minisink and Walpack
buried valleys
, formed from erosion of softer
bedrock
, then passes through the
Delaware Water Gap
in
Kittatinny Mountain
,
[3]
a continuation of
Blue Mountain
in Pennsylvania. The buried valleys extend beyond the riverbed and stretch across the state from Pennsylvania to New York.
[4]
The limestones in this area also exhibit
karst topography
, including sinkholes and small caves.
[3]
Geologic Features
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Notable Rock Formations
[
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]
References
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]
- ^
http://www.state.nj.us/dep/njgs/enviroed/freedwn/psnjmap.pdf
[
bare URL PDF
]
- ^
a
b
c
Orndorff, R.C., et al., (1998). Bedrock Geologic Map of Central and Southern New Jersey. United States Geological Survey, Scale 1:100,000.
- ^
a
b
White, Ron W.; Monteverde, Donald H. (2006-02-01).
"Karst in the Delaware Water Gap National Recreation Area"
(PDF)
.
Unearthing New Jersey Vol. 2, No. 1
. New Jersey Geological Survey
. Retrieved
2008-06-07
.
- ^
White, I.C.; Chance, H.M. (1882).
The geology of Pike and Monroe counties
. Second Geol. Surv. of Penna. Vol. Rept. of Progress, G6. Harrisburg. pp. 53?57.
{{
cite book
}}
: CS1 maint: location missing publisher (
link
)
External links
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]