Passaic Formation gray bed

Rhythmic cycles 2 to 7 m (7-23 ft) of thick gray-bed sequences (Trpg), termed Van Houten cycles by Olsen (1985), contain basal thin-bedded to finely laminated shale to siltstone, which grade upward through laminated to micro-laminated, locally calcareous mudstone to siltstone and finally into massive silty mudstone. Lowest part of cycle has some desiccation features and local fossils; middle part has highest organic content and the most fossils; highest part contains mudcracks, burrows, and root casts. Gray-bed cycles are abundant in lower half of Passaic Formation and less common in upper half.
State New Jersey
Name Passaic Formation gray bed
Geologic age Lower Jurassic and Upper Triassic
Lithologic constituents
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed)
Sedimentary > Clastic > Mudstone (Calcareous)
Sedimentary > Clastic > Mudstone > Shale (Calcareous)
Comments Newark Supergroup, Brunswick Group (Lyttle and Epstein, 1987). The Passaic Formation unit description on the map encompasses multiple units (JTRp, JTRpms, JTRps, JTRpsc, JTRpcq, JTRpcl, and TRpg). The units were split into separate records and appropriate descriptions for each were used. Names for units is from digital map.
NGMDB product
Counties Bergen - Essex - Hudson - Hunterdon - Middlesex - Somerset