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The Newark Group--also known as the Newark Supergroup--is an assemblage of Triassic sedimentary rocks which outcrop intermittently along the United States East Coast; the exposures extend from Massachusetts to North Carolina, with more still in Nova Scotia.

Contents 1 Characteristics 2 Formation 3 See Also 4 Footnotes: 5 External Links:

The Newark Group consists largely of poorly-sorted nonmarine sediments; typical rocks are conglomerate, arkose sandstone, siltstone, and shale.^[1], ^[2] Most of the strata are red beds that feature ripple marks, mud cracks, and even rain drop prints; dinosaur footprints are common, though actual body fossils are very rare.^[3]

The Newark sediments are extremely thick (up to 6 kilometers); they were deposited in a series of half-grabens that were themselves faulted into block mountains.^[4] The beds dip to the east, while the faults dip westward.^[5] The beds are intruded by numerous dikes and sills, indicative of considerable igneous activity; a superb example is the New Jersey Palisades sill.^[6]

The Newark Group's lithologies and structure are the classic hallmarks of a rift valley; the fault-blocking illustrates the crustal extension forces in play during the breakup of Pangea during the late Triassic Period.^[7] The Appalachian Mountains had already been nearly eroded flat by the end of the period; the uplift and faulting that was the first part of the rifting provided new sources of sediment for the vast thicknesses deposited in the Newark Group; the igneous intrusions are similarly diagnostic of a rift valley.^[8] Coarse sediments were deposited near the eastern mountain front, while progressively finer ones were deposited farther west.^[9]

Evidence suggests the climate at the time was subtropical and rainy, though divided between wet and dry months.^[10] A few organic-rich deposits suggest patchy or intermittent swamps and lakes.^[11]

Accumulation of Newark sediments continued from the late Triassic into the early Jurassic..^[12]

• Passaic Formation

1. ^ James Monroe and Reed Wicander, The Changing Earth: Exploring Geology and Evolution, 2nd ed. (Belmont: West Publishing Company, 1997), p. 602.
2. ^ Carl Schuchert and Carl Dunbar, Outlines of Historical Geology, 4th ed. (New York: John Wiley & Sons, Inc., 1947), p. 108.
3. ^ Schuchert and Dunbar, p. 108.
4. ^ Monroe and Wicander, p. 605
5. ^ Ibid.
6. ^ Ibid.
7. ^ Monroe and Wicander, p. 602.
8. ^ Monroe and Wicander, pp. 602,605.
9. ^ Schuchert and Dunbar, p. 109
10. ^ Ibid.
11. ^ Schuchert and Dunbar, pp. 108-9.
12. ^ Monroe and Wicander, p. 602.

• "Materials to Accompany Olsen et al. Science Article." Retrieved on 12/18/06.

• "Newark Supergroup." Retrieved on 12/18/06.