The Newark Basin, that little bit of pinkish-red in the map above, is mostly in New Jersey but represents a rift basin formed by the breakup of Pangaea during the Triassic Period. After the rift a little further to the east broke though, eventually forming the Atlantic Ocean, Africa drifted away from North America and the Newark basin stopped spreading.
A thick pile of sediments accumulated within this basin (along with intrusions of igneous rock like the Palisades Sill). See the red units labeld fanglomerate?
Here's an example near Suffern (and close to the Ramapo Fault). This redbed conglomerate consists of rounded cobbles (of Hudson Highlands gneiss) cemented together with quartz and potassium feldspar grains of sand-sized sediments. It formed as an alluvial fan on the edge of theNewark Basin some 200 million years ago (the greenery is poison ivy).
From there we drove down the Palisades Parkway to the State Line Lookout rest area to view the exposed rocks of the Palisades Sill on the west side of the Hudson.
Turns out that last Saturday, a rather large section of the cliff broke off and collapsed right near where we were (you can see the State Line parking lot in the image below).
A Fox Five news team showed up when we were there and they asked to interview me when they saw I was lecturing to students about geology.
My segment was never aired (guess I'm not pretty enough for TV). When she asked if I was surprised to learn that a segment of the cliff collapsed, I said something like "No, not really. To a geologist it's expected that segments of the jointed cliff face weather and collapse occassionally." Check out the story here.
We then drove across the George Washington Bridge and looked at the Manhattan Formation and Inwood Marble in Washington Heights and then went up to Van Cortlandt Park in the Bronx to see the Fordham Gneiss. Had to love all the little tiny empty baggies on the ground in Inwood Hill Park (once containing crack rocks, I assume).
I'll write more about the geology tomorrow.
Then it was a slow ride back across the Tappan Zee (Friday at 4 pm traffic) and back home.