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Geological Map of New Jersey (1918 Edition)
Overview
The Geologic Map of New Jersey, compiled by J. Volney Lewis and Henry B. Kummel between 1910 and 1912, and published in 1918, presents a detailed and comprehensive view of the state's geological composition. The map is color-coded to differentiate between various rock formations and geological periods, providing a vivid and informative representation of New Jersey's geological diversity.
Color-Coded Geological Units
The map employs a range of colors to denote different rock types and geological periods, which are detailed in the legend:
-
Igneous Rocks:
- Triassic (Newark Group):
- Basalt Flows (Rbs): Represented in reddish-brown, indicating extensive trap rock flows, primarily in the Watchung Mountains.
- Diabase (Rdb): Shown with a pink and red stripe, marking coarse-grained intrusive trap rock sheets and dikes within Newark formations.
- Post-Ordovician:
- Serpentine (sp): Pink, indicating hydrated basic igneous rocks, found in Hoboken and Staten Island.
- Nephelite Syenite (ns): Light brown, highlighting intrusive masses in Sussex County.
- Basic Volcanic Breccia (bb): Yellow, denoting volcanic breccia in Sussex County.
- Triassic (Newark Group):
-
Pre-Cambrian:
- Granite (gr): Dark gray, signifying coarse-grained granite rich in minerals like zircon and titanite, located in northern Sussex County.
- Gabbro (gb): Green, marking hypersthene gabbro and norite near Trenton.
- Losee Gneiss (lgn): Beige, representing granitoid gneiss found in various regions.
- Byram Gneiss (bgn): Gray, depicting granitoid gneiss in areas such as Baltimore and Trenton.
-
Metamorphic Rocks of Unknown Origin:
- Pochuck Gneiss (rgn): Dark brown, likely igneous, containing pyroxene and hornblende.
- Unknown Formation (fnd): Light green, for formations not determined.
Sedimentary Rocks
-
Silurian:
- Late Silurian Formations (Sbd, Shf, Ssg): Various shades of red and gray, indicating formations like the High Falls and Shawangunk Conglomerate.
- Decker Limestone and Longwood Shale (Sd, Sl): Light pink and gray, representing impure limestone and shale.
-
Ordovician:
- Martinsburg Shale (Omb): Dark gray, marking black shale with sandstone beds.
- Jacksonburg Limestone (Ojb): Brown with red stripes, denoting limestone with conglomerate.
-
Cambro-Ordovician:
- Kittatiny Limestone (eOK): Light brown, indicating magnesium limestone.
- Cambrian:
- Hardyston Sandstone (Ch): Light brown, signifying variable sandstone.
-
Pre-Cambrian-Metamorphic:
- Wissahickon Mica Gneiss (Wgn): Light gray with biotite.
-
Devonian:
- Skunnemunk Conglomerate (Dsk): Red, indicating quartz pebbles in matrix.
- Bellvale Sandstone and Pequanac Shale (Dbp): Gray, marking sandstone and shale.
- Marcellus Shale and Onondaga Limestone (Dmo): Dark gray, for fissile shale and limestone.
- Esopus Grit (Des): Brown, representing sandstone.
- Oriskany and Becraft Limestones (Dob): Beige, denoting siliceous and gray limestone.
- New Scotland, Stormville, and Coeymans Formations (Dns): Purple, indicating hard limestone and limey shale.
-
Cretaceous:
- Woodbury Clay (Kwb): Dark green, representing clay.
- Merchantville Clay (Kmr): Black, for glauconitic clay.
- Magothy and Raritan Formations (Km, Kr): Green, indicating sandy clays and glauconite.
Cross-Sectional Profiles
The map features several profile views at the bottom, depicting vertical cross-sections of geological formations across various transects of New Jersey:
- Section A-A: From Dingman's Ferry to Hoboken, highlighting vertical exaggeration and showing detailed layers of geological formations.
- Section B-B: From Poxino Island, Delaware River to Raritan River, demonstrating the sequence and relation of rock types.
- Section C-D: From Bordentown to Peahala, showcasing Cretaceous, Tertiary, and Quaternary strata.
- Section E-E: From Camden to Erial, displaying the stratigraphic layers in detail.
These profiles provide a three-dimensional understanding of the geological structure, revealing the depth and continuity of various rock formations.
