A Natural Resource Management Guide for the County of Morris A ...

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The Cenozoic Era
Erosion and Glaciation Sculpt the Landscape
Between the end of the Mesozoic Era (about 65 million years ago) and the beginning of the Quaternary Ice
Ages (1.75 million years ago), erosion was the primary process shaping the land. Mountain building had
temporarily ceased, and vegetation and forests covered the land, decelerating the erosion. The slight uplift
of the Highlands during the Mesozoic caused streams to run fast and southeastward. They carved out valleys
in softer shales and sandstones and helped form the gently rolling table-top, or peneplain, of Schooleys
Mountain in Washington
Township.
Three glacial advances reached
New Jersey during the
Pleistocene period: the Kansan
(first), the Illinoisan (second),
and the Wisconsinan (third).
The last ice sheets of the
Wisconsinan glaciation retreated
northward about 17,000 years
2
ago. Remnant scars and gouges
on rock outcroppings suggest
that two lobes of ice from the
north (one west and one east)
descended across northern New
Jersey. These lobes met and
stopped in Morris County
somewhere along the ridge of
Stony Brook Mountain in
Kinnelon.
"As the glacier advanced, some
material was deposited beneath it
in hard till beds. Other material
came out at the front of the
glacier whenever melting
overpowered the advance. The
Figure 2 - Terminal Moraine
glacier remained at its maximum
extent long enough to leave a
3
thick deposit of sand, silt, clay, gravel, pebbles, cobbles and boulders called the terminal moraine.” (Figure
2).
2
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3
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15
Geologic History of Morris County