These 3D perspective views of the seafloor bathymetry from multibeam sonar offshore of South Carolina show numerous grooves carved by drifting icebergs. As iceberg keels plow into the seafloor, they dig deep grooves that push aside boulders and piles of sand and mud along their tracks. Sediment cores from nearby buried iceberg scours were used to determine when these icebergs travelled south along the coast. Credit: Jenna Hill, U.S. Geological Survey, Pacific Coastal & Marine Science Center
WHOI has issued the following press release about icebergs and ice ages.
From Woods Hole Oceanographic Institution
June 16, 2021
Woods Hole Oceanographic Institution & United States Geological Survey data shows how icebergs drifted more than 5,000km during the last glaciation
Woods Hole, MA (June 16,2021) — Woods Hole Oceanographic Institution (WHOI) climate modeler Dr. Alan Condron and United States Geological Survey (USGS) research geologist Dr. Jenna Hill have found evidence that massive icebergs from roughly 31,000 years ago drifted more than 5000km (> 3,000 miles) along the eastern United States coast from Northeast Canada all the way to southern Florida. These findings were published today in Nature Communications.
Using high resolution seafloor mapping, radiocarbon dating and a new iceberg model, the team analyzed about 700 iceberg scours (“plow marks” on the seafloor left behind by the bottom parts of icebergs dragging through marine sediment ) from Cape Hatteras, North Carolina to the Florida Keys. The discovery of icebergs in this area opens a door to understanding the interactions between icebergs/glaciers and climate.
“The idea that icebergs can make it to Florida is amazing,” said Condron. “The appearance of scours at such low latitudes is highly unexpected not only because of the exceptionally high melt rates in this region, but also because the scours lie beneath the northward flowing Gulf Stream.”
“We recovered the marine sediment cores from several of these scours, and their ages align with a known period of massive iceberg discharge known as Heinrich Event 3. We also expect that there are younger and older scours features that stem from other discharge events, given that there are hundreds of scours yet to be sampled,” added Hill.
To study how icebergs reached the scour sites, Condron developed a numerical iceberg model that simulates how icebergs drift and melt in the ocean. The model shows that icebergs can only reach the scour sites when massive amounts of glacial meltwater (or glacial outburst floods) are released from Hudson Bay. “These floods create a cold, fast flowing, southward coastal current that carries the icebergs all the way to Florida” says Condron. “The model also produces ‘scouring’ on the seafloor in the same places as the actual scours”
The ocean water temperatures south of Cape Hatteras are about 20-25°C (68-77°F). According to Condron and Hill, for icebergs to reach the subtropical scour locations in this region, they must have drifted against the normal northward direction of flow — the opposite direction to the Gulf Stream. This indicates that the transport of icebergs to the south occurs during large-scale, but brief periods of meltwater discharge.
“What our model suggests is that these icebergs get caught up in the currents created by glacial meltwater, and basically surf their way along the coast. When a large glacial lake dam breaks, and releases huge amounts of fresh water into the ocean, there’s enough water to create these strong coastal currents that basically move the icebergs in the opposite direction to the Gulf Stream, which is no easy task” Condron said.
Read the full press release here.
During the last Ice Age maximum the gulf stream flowed directly east towards Spain not north East towards Great Britain. The current against the Sea ice shelf maximum Was a backflow from east to west therefore the glaciers coming off of the Canadian ice sheet would have been moving with the current as it recycled back towards Florida not contrary to it
Scott-san:
Please check out the below link showing out the cooling Gulf Stream that has been going on for almost a year.
Perhaps this is an indicator the AMO is about to reenter its 30-year cool cycle which will bring much colder temperatures to Europe for decades:
https://www.ospo.noaa.gov/Products/ocean/sst/anomaly/
Could the Heinrich Event 3 icebergs in Florida have originated in Europe, and crossed the Atlantic from east to west?
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003RG000128
We learn something new every day. I have seen a lot of glacial striations, formed by rocks trapped along the bottom of a glacier as it crosses the land, but these scour marks on the sea floor are something new. Makes sense. I wonder if any polar bears went along for the ride: Yeti/Sasquatch, anyone?
Doing seismic interpretaion on the Norwegian sea abd the Norway sector of the North Sea we see these things and recognise the m as such. The Norwegian trench is the mother of all glacial scars but smaller ones are routinely detected and dealt with in pipeline laying operations
The Norwegian trench or Norwegian channel (Norwegian: Norskerenna; Danish: Norskerenden; Swedish: Norska rännan) is an elongated depression in the sea floor off the southern coast of Norway. It reaches from the Stad peninsula in Sogn og Fjordane in the northwest to the Oslofjord in the southeast. The trench is between 50 and 95 kilometres wide and up to 700 metres deep. Off the Rogaland coast it is 250 – 300 metres deep, and its deepest point is off Arendal where it reaches 700 metres deep – an abyss compared to the average depth of the North Sea, which is about 100 metres.
https://sciencenorway.no/geology-ice-age/scientists-are-seeing-ice-age-beginnings-for-very-first-time/1756240
We do a lot of exploration in the Norwegian Barents Sea which has taken scouring to a new limit. Effectively 1000-1200m of what was overburden is gone and the hydrocarbon reservoirs that would normally be around 1000-1500m TVD are now at 300-500m TVD. That’s a lot of missing rock!
There was a bigger bear in town back then…the giant short faced bear…over 10 feet on hind legs…over 1500 pounds. Extinct due to habitat change.
Pretty cool. Would love to do a dive and see some striations on the sea floor.
Patrick, its a lot easier to sit comfortably ashore or in a survey vessel and view sonar records. Two main reasons: 1) Most iceberg scours are much too deep for diving (remember sea level was about 130 m lower) and 2) Visibility is always going to be limited.
You wouldn’t see anything that you could identify as a scour. Most seafloor artifacts are a change in a scale of less than 1 degree.
Ron, iceberg scour features are common on the Newfoundland east coast. In fact they form one of the principle factors in deciding how large an iceberg can occur in the impact zone of offshore platforms. And this how large a fixed platform must be, or how quickly a moored platform must be able to disconnect.
Solutreans were blue-eyed and gracile, not at all shambling Sasquatch.
Yes, bigfoots got tired of the cold & hitched a ride on icebergs to Florida — now known as skunk-apes.
https://en.wikipedia.org/wiki/Skunk_ape
I’m curious as to how deep they estimate the water was when those scours were made. I’ve heard that some icebergs can ground in three hundred feet of water.
Remembering that during maximum glaciation the sea level was as much as 150m (500ft) lower than today, the current depth of the scours should say much about when they were made.
At the estimated time these scours were made (31,000 years ago) a reasonable global sea level estimate is 90m below todays level. The last glacial maximum was 20-22kyr ago with sea levels at 120m below today. So this berg gouging is concluded to have happened on the way into the glacial peak.
I dont understand why modern sediments havent filled these gouges in since then – maybe the sedimentation rates are very low?
As the interglacial period progressed, the shelf was “flooded” with rising sea level waters which shifted the louses of sedimentation eastward toward the modern shorelines. Sedimentation accumulation, as you mover from the present coastline over the shelf and into the deep ocean, decreases rapidly. BTW, 31,000 years is not that long when evaluating sedimentation rates in areas not associated with major river systems.
Bearing in mind that icebergs float with 90% of volume below sea level, a 30 foot tall iceberg-a tiddler as these things go would easily ground in 300 feet but and the Norwgian Trench shows iceberg scour to 700 metres water depth
It’s actually about 7/8ths or 87.5% below the water surface
33000 years ago the ice sheet extended to the Carolinas. Thats where calving would have occurred. And presumably the artic ice sheet extended well down the coast in the Atlantic.
I was at first surprised they didn’t realize the ice sheet was sheet was further south. but then there is modern
educationindoctrination.Were the claims of icebergs seen off the US coast as far south as Florida during the 20th century constructed out of whole cloth?
It’s fascinating to realize that just 12,000 years ago, the area where the UN Building currently stands was under 1 MILE of ice….
Wow.. The UN under 1 mile of ice… Isn’t climate change cool?
As nice as it would be to bury the UN under a mile of ice, I still think reglaciation would be unfortunate. I still think Arrhenius was right, that global warming is net-beneficial.
Still, a sliver lining in every cloud, I guess.
Dr. Happer said Arrhenius is Greta’s great grandfather. CO2 runs in the family!
Unfortunately for Greta, O2 does not.
Several years ago the CBC ran a story, during their weekly radio science show, that claimed that homosapians started the Holocene-interglacial by releasing CO2 through the burning of animal dung.
That’s one of the last times i Iistened to that show.
That was a specimen of Homo Wokticus ;
How Woke People Evolved To Be Superior – YouTube
Klem-san:
Yes, Fascists are renowned experts on all things dung; especially of the bovine variety…
Eddies along the Gulf Stream are common.
The eddies forming along the then Eastern Seaboard would drive icebergs through relatively shallow water.
Eddies forming on the Eastern side of the Gulf Steam would route icebergs through much deeper water. Where it is unlikely icebergs would reach the sea floor, even 31,000 years ago.
e.g.;
Seems to me that with sea level that much lower, the gulf stream would have been much further to the east during those times. And, if I recall, the near shore current is from north to south, which at that point in time would have been the current moving the bergs.
ahhh… the Heimlich manoeuvre. What goes around comes around.
Do you guys spell plough differently too? Never realised! (Along with gaol, tyre, -ised words, and honour, colour etc)
You’ll find that a lot of these words are actually the way they were spelt originally in England. The USA didn’t change, but the UK did, probably because of European influences. Think ‘centre’ vs ‘center’ for example.
The USA is basically more conservative, and still uses imperial measurement (mostly).
The only real difference that I’m aware of (not a philologist, but know how to spell it!) is Aluminum, but that was merely a mistake that got propagated.
How fortunate Britain is to have us preserving traces of its ancient language.
Since those words look slightly French, the question is what Napoleon called the incredibly rare metal he served dinner on.
“Mine.”
I understand it is common in linguistics for an emigré population to “freeze” a language. Thus Quebec French is like 17th century French, Mennonite communities speak old German. And so on.
Some might be, off shoot languages do fossilise, but it is also true that one of your chaps, Webster or someone like that, reworked the language to simplify it, which is where you got color and center from.
(We always used the french spelling for centre, it is where the word came from, we do tend to respect foreign words and leave them unchanged. )
Anyway, with Brexit we are bringing back some imperial measures, such as the pound, as an option. We always kept the pint and punnet though!
Speaking of ice: “10,000 Years of Climate Memory Have Been Preserved in The Oldest Ice From The Alps”
https://www.msn.com/en-us/news/technology/10-000-years-of-climate-memory-have-been-preserved-in-the-oldest-ice-from-the-alps/ar-AAL8ipL
The routing of meltwater into the subtropics – a location very far south of these regions – implies that the influence of meltwater on global climate is more complex than previously thought,
Poor old ignorant cave men didn’t realize they were doomed with all that warmening going on. Thankfully we’re a lot smarter than than that nowadays…..?
usually, when something afloat runs aground, it is stopped.
when glaciers carve out traces, it is because of the massive weight of ice.
yet something pushed these floating icebergs hard enough that when they ran aground, instead of stopping, they plowed the sea floor for incredible distances.
something else that seems odd to me is the lack of tumbling. wind and currents are pushing and the lowest tip is resisting that push.
and shouldn’t the ice be losing in this rock ice collision? again, the massive weight and constant supply of ice is why glaciers carve out solid rock.
well, my thoughts are moot. after all, they say they have a model. and we all know that models must always be right.
90% of the mass of icebergs is below the water line.
That provides for a lot of stability.
icebergs roll over. it happens quite frequently. even with 90% below water they roll over. even without the lowest part dragging on the bottom and the mid and upper parts being pushed on, icebergs roll over.
I don’t know though what happens to massive break away ice sheets. Something so much longer and wider than it is deep would be unlikely to roll over. I can imagine though the giant icequake when such a thing collides. Fractures, calving and even breaking apart would be possibilities.
then after surviving the collision, the force pushing it has to be so great that it acts like a plow. but this plow isn’t steel, it is ice. and the plow part of the ice has to survive plowing sea floor over huge distances.
I suspect that sediment cores from the Florida straits would reveal the telltale signatures of melting bergs in the form of cobbles and glacial debris dropped by the bergs as they melted. Imagine finding such evidence in the Caribbean!
You are correct Scott. As a Tech hand on the Ocean Drilling Program Joides Resolution, we commonly found dropstones in the subsea cores we recovered , that and fossils, wood and even rarely, meteorite fragments.
As I was a child, around the time I learned to read a year before going to school in the end 50ies I remember to have often read in spring and early summer of floating icebergs, some as southward as the Gulf of Biscaya. Seems to have been usual at these times.
How would meltwater from Hudson Bay get into the Atlantic Ocean without traveling all the way around Labrador? During a period of massive glaciation, sea levels would have been lower than they are now.
From the above article:
” “The idea that icebergs can make it to Florida is amazing,’ said Condron. ‘The appearance of scours at such low latitudes is highly unexpected not only because of the exceptionally high melt rates in this region, but also because the scours lie beneath the northward flowing Gulf Stream.’ ”
Uhhhh . . . . any consideration given—any at all—to the idea that perhaps the Gulf Stream was NOT flowing northward along the eastern coast of the US 31,000 years ago? You know, that just might explain how icebergs do not have the capability to “drift” against a rather strong subsurface current that affects about 90% of their surface area.
And what’s with the statement about “exceptionally high melt rates in this region”??? The Woods Hole Oceanographic Institution press release goes on to state: “The ocean water temperatures south of Cape Hatteras are about 20-25°C (68-77°F).”
Whoever wrote this tripe for Woods Hole appears to be asserting that the western Atlantic ocean today is little different than it was 31,000 years ago . . . you know, the period when Earth was deep in an GLACIAL environment (aka “stadial”, or ice age, climate).
Good grief!
That’s the beauty of modeling…you gets to set you’re own rules and boundaries!