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

• nearN40 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.

• nearN40 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 ReservoirLebanon 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 Formationcontinue 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 redbedsNorth of Milford along the river

• Perkasie Member of the Passaic FormationRed conglomerate and sandstonenear N40 34.546 W75 07.796Find 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