Some northern NJ and vicinity
outcrops
• Northern New Jersey has very diverse geology.
Unlike the southern part of the state, northern
rocks are consolidated, faulted, and folded.
• A map of Northern New Jersey is here
• Cross sections are here
• A pamphlet is here
• These will help you interpret what you find
•
All Pictures can be expanded
• You can stretch the attached pictures from
Google Earth by clicking the picture and
dragging the corners
Triassic and Jurassic Lowlands
• Our campus resides in the western half of the rift that
opened the Atlantic. The rocks are redbeds: fine
sandstones, siltstones and mudrocks from and as
laterites. Much of the material was eroded off of the
highlands and escarpment to the north-northeast.
Along Rts. 22, 78 and Long Hill are Jurassic lava flows.
These are mined for basalt trap rock. In Princeton and
Flemington rift valley lakes are preserved. There is a
Diabase ring dike at Round Valley, and along the
Delaware a trip from Stockton through Milford to
Holland provides a journey up-section from the basal
sands, through the lakes, to redbeds, to the border
breccias.
Tr\J Basalts
• Scotch Plains Rt.
22, turn right past
McDonalds, note
quarry, right onto
New Providence
Road, follow road
along stream to
light, then either
1. turn right and
immediate right
into parking.
• OR
• 2. instead go
straight, continue
up Diamond Hill
Rd., pass 78, turn
around. Before 78
entrance note
small road along
outcrops, on right.
Basalts - Watchung
•
Rt. 22 West to Watchung exit,
follow stream on left, note
former quarry walls on right.
•
Orange Mountain Basalt at the
Donald R. Scotti Public Works,
880 Somerset Road, Watchung,
NJ. N40 38.089' W74 26.833'.
Permission and Hard Hats
required. Contact the Site
Supervisor in person. There are
two lava flows here. The lower
basalt had a normal dark, high
strength traprock appearance
with ~8 cm circular vugs that
mostly contained calcite. The
upper flow had a green
appearance with irregularly
shaped mineralizations and
numerous 1 mm vesicles; it
appeared weathered and was
softer.
Basalts @ Bound Brook - Chimney Rock Rd.
• Rt. 22 exit Thompson
Avenue, becomes
Chimney Rock Road,
drive past quarry along
stream, then left bend,
take small parking
pulloff on right. Follow
stream north, note
four Basalt layers cliff
on left
• near
N40 35.105' W 74 33.403
Round Valley Reservoir, Lebanon, NJ
• 3. Early Jurassic Diabase, Cherry St., Round Valley Reservoir,
Lebanon, NJ, near the dam. You MAY NOT STOP AT THE OUTCROPS
without PRIOR permission from the park police, (908) 236-6355.
• near
N40 37.952' W 74 50.089.
• Diabases have the same composition as basalt and gabbro, and
have visible but fine crystals and ophitic texture (Augite surrounds
Plagioclase crystals). Recall the shallow depths of Diabase dikes and
sills and their roles as feeders to surface lavas. Look at the Northern
NJ Geologic Map (link on slide 1) and noted the ring shape of this
one. We talked in class about gravity settling of early forming
crystals in the Palisades Sill Diabase exposed along the Hudson
River, and the fractionation of the remaining magma that results.
Round Valley Reservoir
Lebanon NJ near Rt. 22, find Cherry Street, turn
south into park.
YOU MAY NOT STOP NEAR THE DAM WITHOUT
PRIOR PERMISSION
Central and Southern New Jersey Maps
• Stockton and the Lockatong locality listed
along Rt. 29 happen to fall on the extreme NW
corner of this map.
Stockton Fm., Raven Rock NJ
• Go To Stockton, NJ, on Rt. 29
• Take US 29 along Delaware River north to Raven Rock
cont. north to N40 24.781' W75 02.265‘, red SS with
poor bedding
Lockatong Formation
• Lockatong Formation
continue north along 29 to near N40 26.85' W75 03.9
Milford, NJ
• Continue north along 29 to Milford, turn left
onto Bridge Street, then right to Church
Street, left at the church to Riegelsville Road
(aka Riegelsville-Milford Road.)
Passaic Fm., mostly redbeds
North of Milford along the river
• Perkasie Member of the Passaic Formation
Red conglomerate and sandstone
near N40 34.546 W75 07.796
Find bus-sized pulloffs, keep away from the road!
As you travel along these outcrops, notice an
increase in maximum particle size, from sands near
Milford, to cobbles here, then to boulders closer to
the border fault.
Hammer Creek Conglomerate
Holland NJ near the fault
• Continue on Riegelsville Road to Church Road on right near
N 40 34.453, W 75 11.172. At the corner note the low
outcrops of carbonate breccia. Just further north along
Riegelsville Road note the Leithsville Carbonates, then the
Orthogneisses of the Grenvillian pC province, the Highlands
Holland NJ near the fault
Flemington NJ Lockatong\Orange Mt.
Basalt contact metamorphism
• Go to Flemington, NJ. Take Rt. 12 West to Old
Croton Rd, turn right onto Capner St., pull into
parking lot at Mine Brook Park. Cross Capner
and take the Dolores Morales Nature Trails
(about 100 meters) you will start to see side
paths to a shallow part of the stream. Across
the stream the Orange Mountain Basalt covers
the Lockatong Argillite. Note the discoloration
in the Argillite near the contact with the
overlying lava flow.
Flemington NJ Lockatong\Orange Mt.
Basalt contact metamorphism
• Dolores Morales Nature Trails, near Mine Brook Park, Capner
St., Flemington NJ.
Lockatong Fm. and Orange Mtn. Basalt.
• Here the dips are great enough that we can see the contacts
between the lava flows and the basalt.
• Examine the contact metamorphism of the local
red Lockatong into gray hornfels, caused by the heat of the
basalt that flowed over it. Note the explosion breccia features
in the basalt as the water in the sediment flashed to steam. In
some places the cracks are filled with Calcite. Copper sulphate
mineralization is present in the redbed / hornfels boundary
within the Lockatong. Mudcrack specimens can be found in
the river bed.
• Near N40 30.773' W74 52.452. Use the trail across from
Parking, and also cross the stream and walk upstream along
the bank for explosion breccias.
Flemington NJ Lockatong\Orange Mt.
Basalt contact metamorphism