New Jersey Pleistocene

[jpevahouse]

A subject of special interest to me over the last few years is the Pleistocene era in New Jersey. Pleistocene fauna as documented by various institutions and paleontologist has a few interesting omissions when compared to other areas of the country.

Though Pleistocene fossils are occasionally found on land the most prolific source has been fossils dredged from the continental shelf by commerical fishing. The documented animals are mastodon, mammoth, moose elk, giant ground sloth, caribou, tapir and walrus. Of these mastodon remains are the most common, mammoth remains very scarce, the others not too common but have been found. Animals remains not documented are horse, bison, camel and peccary. A pattern appears which suggest the NJ terrain during the late Pleistocene era did not attract grazing animals, yet the extensive wooded areas attracted browsing animals like the mastodon.

What's interesting is that sites like the Port Kennedy site just across the Delaware River and the Cumberland Cave site just south in Maryland contain a wider array of Pleistocene animals including abundant peccary and tapir remains.

There exists one manatee bone from the NJ continental shelf verified by scientists as the northern most example ever found of this animal which liked a more tropical like environment.

There is of course the numerous specimens surely in private collections. Paleontology in NJ goes back to the pre Civil War era and a lot of early finds were not well documented and often came from secondary accounts. Frequently early fossils were included in reports but lost over time and inaccessible for examination today. A good example is a horse mandible found during the late 1800s at the Fish House sediments near Camden. It was found by workers excavating clay for brick making and no professional saw the actual context in which the jaw was found. Later the jaw was lost and has not been seen in over 100 years. The site was destroyed by mining over 100 years ago, so even the site is not available for examination. This is the only example of horse remains I found to be on the record. The question is, how reliable is the horse jaw as a paleontology specimen? Not very good in my opinion as is true with a lot of fossils taken from their original context and inaccessible for examination by professionals.

Edited August 17, 2015 by jpevahouse

[Al Dente]

There exists one manatee bone from the NJ continental shelf verified by scientists as the northern most example ever found of this animal which liked a more tropical like environment.

The summer range of manatees extends along much of the Atlantic Coast and includes recent sightings in New Jersey, Rhode Island and Massachusetts. I realize you are referring to fossil occurrence but I wouldn't be surprised if Pleistocene remains are some day found in these states.

[Shellseeker]

Thanks for this post. A discussion and summary of fossils connected to a place and geological period of time, done by one with some expertise is always interesting and welcome.

I am somewhat conflicted on the issue of who should own control of Paleontological resources. It is not that I am over_trustful of fossil hunters. It just that we have too many examples where the combination of special interest groups, politicians, lawyers and even scientists have created dubious regulations that serve no one but themselves. I keep in mind the Bone Wars with Cope and Marsh, a period of time where I would not begrudge a horse mandible with teeth to a private collector in New Jersey.

A subject of special interest to me over the last few years is the Pleistocene era in New Jersey. Pleistocene fauna as documented by various institutions and paleontologist has a few interesting omissions when compared to other areas of the country.

[FLINTandBONE]

I was just researching the geologic map of New Jersey the other day since I have family in Wildwood and the Villas and spent many of my summers there as a kid. I was surprised to see how much area is Holocene and Tertiary. That explains where all of the Mammoth and Mastodon stuff comes from. I can confirm that the dredgers and scallopers bring up a lot of material since my brother has worked for several commercial fishing outfits there and they regularly pull in all sorts of teeth and tusks. He told me some of the captains even have whole tusks that they found, needless to say that had my interest piqued. I am still awaiting two teeth that he has for me in storage at our dads place, from his description they are Mastodon.

What I would like to know is if anyone dives for and finds this type of stuff like in the Florida boneyard or is the material too sparse and/or the conditions too poor.

[Auspex]

All that Pleistocene terrestrial material is dredged up offshore along the Mid Atlantic because that was dry land during the peak Ice Ages; lower sea levels, y'know.

[jpevahouse]

I was just researching the geologic map of New Jersey the other day since I have family in Wildwood and the Villas and spent many of my summers there as a kid. I was surprised to see how much area is Holocene and Tertiary. That explains where all of the Mammoth and Mastodon stuff comes from. I can confirm that the dredgers and scallopers bring up a lot of material since my brother has worked for several commercial fishing outfits there and they regularly pull in all sorts of teeth and tusks. He told me some of the captains even have whole tusks that they found, needless to say that had my interest piqued. I am still awaiting two teeth that he has for me in storage at our dads place, from his description they are Mastodon.

What I would like to know is if anyone dives for and finds this type of stuff like in the Florida boneyard or is the material too sparse and/or the conditions too poor.

The first NJ mastodon molar I saw years ago was on the docks at Point Pleasant. That got my attention and I've had a strong interest since. What I see and hear is Pleistocene remains are occasional finds by fisherman. One fisherman described it as "Not very often." which is consistent with the trickle I see of yearly finds. The NJ shore is not anything like the prolific fossil bearing streams and beaches of Florida.

The rakes of the clam and scallop trawlers only penetrate the bottom a few inches at best. Who knows what lies deeper though sand dredging doesn't seem to bring up very much. The most common finds seem to come from 20 to 40 miles offshore though there are reports of finds along the extremes of the continental shelf. Holgate I hear has a near shore Pleistocene deposit about 20 feet down but it's rare to find remains washed ashore.

Edited August 18, 2015 by jpevahouse

[jpevahouse]

What I would like to know is if anyone dives for and finds this type of stuff like in the Florida boneyard or is the material too sparse and/or the conditions too poor.

There are occasional finds by divers along the NJ shore. I had a mastodon molar found by scuba diving.

[jpevahouse]

All that Pleistocene terrestrial material is dredged up offshore along the Mid Atlantic because that was dry land during the peak Ice Ages; lower sea levels, y'know.

The ocean level dropped 300 ft during the last ice age exposing about 90 miles of the NJ continental shelf. However, there are other reasons for the presence of fossil bones off the NJ coast. There were three major river delta systems during the late Pleistocene which carried vast amounts of inland sediments eastward onto the exposed continental shelf.

I've come to suspect the exposed continental shelf was a hostile area for most land mammals, a swampy marshland of coves, inlets, barrier islands. It would have been a death trap for large mammals like mastodons whose remains seem the most commonly found.

[Auspex]

It would have simply been a 90 mile extension of the current coastal plane; there is no good reason to think of it as a marshy death trap.

[Plax]

Indeed, there was quite a bit of topography

[jpevahouse]

It would have simply been a 90 mile extension of the current coastal plane; there is no good reason to think of it as a marshy death trap.

Much of the current NJ coast line today is seperated from dry land by extensive marshes which can reach miles inland. Most beach resort areas are on barrier islands parallel to the shoreline managed to accomodate tourists. I read geologists speculate the rise and fall in the ocean level occurred relatively quickly. Of course the continental shelf was exposed for several thousand years and surely there were many changes in the topography. I can only guess how the area would have actually looked.

Geologist do agree that at the end of the ice sheet vast inland sediments were washed into the Atlantic Ocean.

Edited August 18, 2015 by jpevahouse

[Auspex]

I am sure that there were barrier islands, sounds, and tidal marshes, but the extent would have been 4-5 miles max. The rest would have been terra firma, just like today.

[Al Dente]

I am sure that there were barrier islands, sounds, and tidal marshes, but the extent would have been 4-5 miles max. The rest would have been terra firma, just like today.

I agree.

Here's an illustration that gives a good idea on the topography of the shelf area.

[jpevahouse]

It's important to keep in mind the bottom surface of the continental shelf today is not the ice age era surface. Extensive post glacial erosion from the Atlantic coastal plain deposited millions of tons of sediments on the continental shelf. Fossils recovered today are a mix of bones washed from inland mixed with bones already on the shelf.

[squali]

The glacial sediments were deposited by rivers that have been obscured by coastal erosion as the sea regressed.

Picture south jersey today with a longer ride to the shore.

[Auspex]

The Quaternary sediment loads are most significant in the river deltas, less so on most of the shelf itself. Of course, there is ongoing redistribution by the longshore current.

[Plax]

actually I would say that the present sea floor off NJ is mostly the land surface (or slightly covered surface) of the late Pleistocene. Sea level rose almost immediately after the end of the last glaciation. Clammers and scallopers only dredge very shallowly on the sea floor finding pleistocene fossils. Off NC we have the same situation with hardly any sediment covering outcropping Miocene sediment where collectors dive for meg teeth. That Miocene exposure was eroding on land during the much longer glacial periods. The Cape Fear River at that time was depositing its sediment load far out to sea.

[jpevahouse]

Every year my wife and I vacation at Cape May, NJ. I always stop by a shop in the area where I usually buy off shore fossils dredged by local fisherman. Just got back and my find this year is a section of walrus skull with proximal end of tusk and two teeth. See photos.

Those the photos don't show the full size of the fossil I would estimate it's about 1/3 of the skull, the left side, right side and back missing. The tusk was broken off long ago with some recent damage but the upper 3 to 4 inches is still embedded in the skull. These little bean shapped teeth are usually missing, so it's a nice feature to have.

[jpevahouse]

I agree.

Here's an illustration that gives a good idea on the topography of the shelf area.

jersey.jpg

I read through two or three NJ State reports on the Pleistocene geology of the NJ continental shelf. What I found was:

During the period of the last Wisconsinan ice sheet the mouth of the Hudson River was located about 80 miles south of it's present location. During the warming and melting phase which began about 12,000 years ago large stores of water blocked by ice along the Hudson Valley were released and flooded the NJ continental shelf with massive sediments. This event was described as a "catastrophic event". At this time the ocean level was rising due to the melt of the ice sheet. Today the Hudson Shelf Valley is a large underwater valley extending south east across the NJ continental shelf.

It can be assumed the pre 12,000 year surface of the NJ continental shelf was covered by massive sediments mostly washed in from the north. Much of the surface of the bottom of the present continental shelf was not likely dry land due to the quickly rising ocean level.

I also read in other geology reports regarding ice age deposits that during the period of the massive northern ice sheets there was actually more erosion than sediments. Old deposits were destroyed by newly advancing ice sheets. There were four periods of ice sheets during the 1.8 million years of the Pleistocene era. The last ice sheet lasted from about 85,000 to10,000 years ago with the maximum ice accumulation between 25,000 and 21,000 years ago.

Edited September 25, 2015 by jpevahouse