The Shark River, named that way because a shark took a person off a dock in colonial times (I won't swim near its mouth), kind of doesn't fit. I understand there are hills where Raritan Bay meets Atlantic Highlands, due south of Manhattan, because it was once a high valley wall on the south side of the Hudson River. But the Shark River is 12 miles or so south of those hills. It is about 800 acres in size and very round. Shark River Hills is in the middle, with a maximum elevation of 59 feet. It's not a river at all really. It doesn't fit because it falls in the middle of a coastal area formed, geologically speaking, as the ocean advanced and receded as much as 70 miles during the ice ages. The area is pretty flat with rivers and streams that drain off into the sea.
I just read a fascinating study that focused on a geological formation called a Carolina Bay. In New Jersey they are called a "spung," with their origin by no means settled among geologists. There are 50,000 of them from New Jersey to Alabama. Some recent scholarship suggests they were formed from an extraterrestrial object that impacted or exploded above the ice sheet near Hudson Bay or Lake Michigan about 13,000 years ago. The hypothesis targets these initial impact areas, because of the Carolina Bay ovals point back to the ejecta origination point. Here in NJ, the Carolina bays orient from northwest to southeast.
The Geologists in this particular took samples from the margins of Carolina Bays. They identified materials that had been heated to as high as 2,200 degrees. Temperatures this high occur only with a lightning strike, nuclear explosion or an extraterrestrial impact. They conclude that multiple impacts of extraterrestrial origin took place just before the Younger Dryas.
During the Younger Dryas there was a rapid return to glacial conditions, following a legnthy period of warming. It lead to Holocene megafauna extinctions that included large critters like mastodons and mammoths, as well as larger carnivores like sabre tooth tigers, that probably viewed humans as Malthusian snacks. I don't think humans killed off megafauna. It makes sense to me that extinction of megafauna predators allowed the human population to go parabolic.
I like this study, because it confounds the hypothesis that melting ice draining into the north Atlantic stopped the Atlantic conveyor, causing the Younger Dryas. The wackos will tell you that global warming will cause an ice age for this very reason. So choke on this one you morons.
To me, the Shark River looks like an impact crater with a central peak. It is oriented in the right direction to be the result of ejecta from a bigger impact. I can be totally wrong, but I can't help imagine that must have been on helluva an ice ball that landed here, not all that long before recorded history and Lindsay Lohan.
Update - I am now thinking that the Shark River is an impact site, but not a crater with a central peak. The ejecta from the Saginaw Manifold would have included a lot of ice, which was probably pretty slushy when it hit the ground after being off the ground for six minutes. This is why Carolina Bays are not so deep. So after reflecting on this, Shark River Hills was a preexisting formation on the poximal end of the ejecta landing spot.