Hiding In Plain Sight

If the Younger Dryas climate event was caused by fragments of comets hitting North America around 10890 BCE (a theory which looks increasingly convincing), where are the craters?

This is a question that its proponents largely leave unanswered.

Short Answer

The obvious answer is that they are hiding in plain sight.

The Great Lakes and a group of three Lakes in the Northwest Canada look like plausible candidates for Younger Dryas Impact craters. 

Most of the Great Lakes are obvious good fits for this hypothesis due to features that make them unique in the world as are a couple of the Northwest Canadian Lakes. They are very deep and large where their conventional creation stories do not provide compelling support for either of these features, in the right place in North America beneath the former Laurentide Ice Sheet. Both groups of lakes were "born" in the Younger Dryas.

In the Northwest Canada case and the Lake Erie cases, an analysis of how the lakes have evolved from Younger Dryas era Paleo-Lakes which were quite different from those we observe today makes the case clearer. 

The three lakes in the Northwest Canada are derived from a single historic Lake Peace that came into being around the time of the Younger Dryas. Lake Erie was more than three times as deep as it is today at the time of the Younger Dryas, but then was filled with sediment.

One can easily imagine a 1000 meter asteroid or comet fragment breaking into two pieces, the smaller of which on a more directly downward angle formed ancient Glacial Lake Peace, and the larger of which after fragmenting further close to the point of impact at more of an angle to the surface of the Earth, formed the predecessors to today's Great Lakes.

Note On The Younger Dryas Impact Theory

An ancient temple in South-Central Turkey (putting a date stamp on the event with pictograms that correspond to historical astronomy) and Hopi legends (about the end of the first world in fire plunging them into a cold era interpreted likewise here) both tend to corroborate this theory as does physical evidence of impact debris in North America, and astronomy evidence. The sudden onset and relatively short duration of this severe climate event also tend to corroborate the theory, although other options related to a disruption of Atlantic Ocean currents by glacial meltwater have been proposed but not directly confirmed.

Determining exactly why and how the climate impacts of the Younger Dryas transpired isn't simply a matter of historical interest. This event is one of the best available proxies for how global climate behaves in periods of abrupt change that serves as source data for models interpreting how human air pollution is leading to global warming. And, if we misinterpret what was going on in the Younger Dryas, our climate models may also be less accurate than they could be with a more accurate analysis.

The Younger Dryas had a global impact, for example, giving rise to a severe drought in Southern Taiwan.

A Full Analysis:

Some of the data points here come from the 2017 World Almanac which may differ somewhat from the linked sources, but are preferred for sake of consistency.

Parameters

They should be more shallow and smaller in extent than the Gulf of Mexico caused by an impact with an object ten times as large, while still being quite large and quite deep, sixty-six million years ago.

The Gulf of Mexico is 582,100 square miles in area and 5,297 feet deep. Our craters should be more shallow and smaller in expanse than this. The crater itself is at least 180 km in diameter and more than 2,000 to 3,600 feet deep).

Ideally it should be in North America beneath the former Laurentide Ice Sheet. This fits with the area where megafauna extinction and observable impact on archeological human cultures was greatest. 

Members of the North American Clovis culture were roaming North America at the time all of this happened and saw it with their own eyes (although obviously not with a modern understanding of the events). Their culture collapsed as a result of the Younger Dryas climate event.

Any crater will ultimately be filled with water unless it is in a deep desert, and even then it must be quite deep to fit these parameters and must not be related to volcanic activity. No dry craters in North America fit these parameters, although such craters are known elsewhere in the world. Known examples are the wrong size and the wrong age, such as a famous one in the Arizona desert. The craters closest to the right time are the Rio Cuarto craters, which are too young, too small (4.5 km in diameter) and in the wrong place (Argentina about 10,000 years ago) and the Tenoumer Crater in the Sahara desert which is probably too old  but close enough in time (21,400 ± 9,700 years) but too small (1.9 km in diameter and 900 to 1200 feet deep from what would have been a 1 km object moving at high speed) and in the wrong place.

Ruling Out Possibilities

There is no good reason for these craters to be in the ring of fire or otherwise on a boundary between or at the edge of continents, unlike the Mediterranean Sea, the Black Sea, the Caspian Sea (once connected to the Mediterranean and Black Seas and now an endorheic basin), the Red Sea (in a rift valley), the Bering Sea, the Gulf of California (in a rift valley), the Caribbean Sea, and Lake Maracaibo in Venezuela (really a bay of the Caribbean Sea).

Yet, they should also not be a shallow flooded plains adjacent to seas or oceans like Hudson Bay (281,900 square miles and 305 feet deep on average), the Persian Gulf (88,800 square miles and 326 feet deep on average), the East China Sea (256,600 square miles but 620 feet deep), the North Sea (164,900 square miles and 308 feet deep), the Baltic Sea (147,500 square miles and 180 feet deep), and the Yellow Sea (113,500 square miles and 121 feet deep), and the Aral Sea (4,040 square miles and 180 feet deep). 

Lake Ladoga (6,835 square mile basin, 738 feet deep) at an elevation of 13 feet is an edge case, but looks a lot like an extension of the Gulf of Finland (which is in turn an extension of the Baltic Sea) into which it drains. Lake Onega (connected by water to the Baltic Sea and 98 feet deep), Lake Nicaragua, and Lake Iliamna in Southeast Alaska are similar cases.

It should also not be in rift valleys Lake Baikal (in Siberia) which like Lake Tanganyika was formed as an ancient rift valley (it is 25 million years old and is the largest and deepest freshwater lake in the world) and the Great Lakes of the African Rift Valley: Lake Victoria, Lake Tanganyika, Lake Turkana, Lake Nyasa, and Lake Albert.  Nor, should they be collapsed volcanos like Crater Lake in Oregon.

Inland shallow flooded depressions with drainage are poor candidates. These include Lake Manitoba (21 feet deep) and Lake Winnipegosis in Canada (38 feet deep).

Two edge cases are:

* Lake Winnipeg (9,416 square mile basin, 200 feet deep) at an elevation of 712 feet
* Reindeer Lake (2,568 square mile basin, 720 feet deep) at an elevation of 1,106 feet

But, these are much shallower than the viable candidates identified below, do not have a depth below sea level, and are at fairly high elevations relative to the surrounding territory, without having clear connections to other viable candidates.  In other words, these are probably just classic natural reservoir lakes.

Endorheic basins are also poor candidates as these would form even in the absence of an impact. Many are also shallow. These include Lake Chad (24 feet deep), Lake Eyre in Australia (4 feet deep), the Great Salt Lake (16 feet deep), Lake Balkhash in Kazakhstan (85 feet deep), and Lake Titcaca (much deeper because its high elevation limits evaporation losses) "at the northern end of the endorheic Altiplano basin high in the Andes on the border of Peru and Bolivia."

Considering Viable Possibilities

What fits the bill? 

Deep lakes, dug below sea level, in the midst of flat plains in areas that are not geologically active where there is no obvious geological mechanism other than an extraterrestrial impact to create such a deep gash in the Earth, ideally in North America after vaporizing parts of the Laurentide Ice Sheet. 

Two clusters of lakes in North America, the Great Lakes, and a cluster of lakes in Northwest Canada, fit this bill, while essentially no lakes or systems of lakes anywhere else in the world fit these parameters. The North American lakes are also known geologically to date from around the Younger Dryas after eons under ice sheets, so their "birthdates" are just right.

If these lakes were caused by glacial advance and retreat scouring away bedrock below them, as conventional wisdom claims, there should be similar lakes in Northern Europe and Asia. But, there are no comparable like to them in Eurasia or really anywhere else in the world as explained below in an analysis of all of the largest lakes and seas in the world.

The Great Lakes

It is easy to imagine a large part of a 1000 meter comet fragment breaking up not far from impact and producing the following four Great Lakes (and quite possibly Lake Erie as well in its prior incarnations as Lake Warren and Lake Wayne, see below) as impact craters after vaporizing the remaining glacier cover above them.

* Lake Superior (20,600 square miles, 1333 feet deep) at an elevation of 601 feet above sea level
* Lake Michigan (22,300 square miles, 923 feet deep) at an elevation of 578 feet
* Lake Huron (9,100 square miles, 750 feet deep) at an elevation of 578 feet
* Lake Ontario (3,460 square miles, 802 feet deep) at an elevation of 243 feet
* Lake Erie (4,980 square miles, 210 feet deep) at an elevation of 569 feet

The geology of Lake Superior is some of the deepest bedrock in the world, although the conventional explanation for this does not resort to an extraterrestrial impact. Conventional wisdom in geology says that Lake Ontario was carved from weak stone in the last ice age by glacial ice sheets, but it is awfully deep for that kind of excavation (which makes far more sense in the case of Lake Erie). The oldest evidence of human use of the land bridge that runs through Lake Huron when lake levels are low is from 7,000 BCE (almost 4,000 years after the Younger Dryas and about 7,000 years after Native Americans ventured into North America).

The early predecessor of Lake Huron is known as Lake Algonquin.

The lake in existence from around the time of the Younger Dryas where Lake Ontario is today was called Glacial Lake Iroquois, which drained via the Hudson River into the Atlantic Ocean.

(The references in these lake names to Indian tribes present in these areas at the time of European first contact is, of course, anachronistic.)

Lake Erie looks more like a bloated river that developed high banks over time as glaciers melted that connected Lake Huron to Lake Ontario. But, the geology of Lake Erie may give it a common Younger Dryas impact origin with the other Great Lakes. Wikipedia has this to say about the geology of Lake Erie:

Lake Erie was carved out by glacier ice, and in its current form is less than 4,000 years old, which is a short span in geological terms. Before this, the land on which the lake now sits went through several complex stages. A large lowland basin formed over two million years ago as a result of an eastern flowing river that existed well before the Pleistocene ice ages. This ancient drainage system was destroyed by the first major glacier in the area, while it deepened and enlarged the lowland areas, allowing water to settle and form a lake. The glaciers were able to carve away more land on the eastern side of the lowland because the bedrock is made of shale which is softer than the carbonate rocks of dolomite and limestone on the western side. Thus, the eastern and central basins of the modern lake are much deeper than the western basin, which averages only 25 feet (7.6 m) deep and is rich in nutrients and fish. Lake Erie is the shallowest of the Great Lakes because the ice was relatively thin and lacked erosion power when it reached that far south, according to one view. 

As many as three glaciers advanced and retreated over the land causing temporary lakes to form in the time periods in between each of them. Because each lake had a different volume of water their shorelines rested at differing elevations. The last of these lakes to form, Lake Warren, existed between about 13,000 and 12,000 years ago. It was deeper than the current Lake Erie, so its shoreline existed about eight miles (13 km) inland from the modern one. The shorelines of these lakes left behind high ground sand ridges that cut through swamps and were used as trails for Indians and later, pioneers. These trails became primitive roads which were eventually paved. U.S. Route 30 west of Delphos and U.S. Route 20 west of Norwalk and east of Cleveland were formed in this manner. One can still see some of these ancient sand dunes that formed in the Oak Openings Region in Northwestern Ohio. There, the sandy dry lake bed soil was not enough to support large trees with the exception of a few species of oaks, forming a rare oak savanna.

Lake Warren (actually three separate lakes) which formed right around the time of the Younger Dryas was comparable in depth to the other Great Lakes, a hypothesis consistent with these lakes as Younger Dryas impact craters. Lake Wayne formed at about the same time is also consistent with this hypothesis and much deeper than the current Lake Erie which apparently had its bottom filled with silt (i.e. crude scooped up by the melting glacier at its leading edge and deposited when it melted).

Lake Warren and Lake Wayne were more than three times as deep as modern Lake Erie.

Three Related Lakes In Northwest Canada

* Great Bear Lake (12,096 square mile basin, 1,463 feet deep) at an elevation of 512 feet
* Great Slave Lake (11,030 square mile basin, 2,014 feet deep) at an elevation of 512 feet
* Lake Athabasca (3,064 square mile basin, 407 feet deep) at an elevation of 699 feet

These lakes have a common origin in Glacial Lake Peace which came into being at the moment of the Younger Dryas and could have been formed by a single impact in a second major fragment apart from the one that formed the Great Lakes.

The conventional explanation for the geology of Great Bear Lake is as follows:

Great Bear Lake lies between two major physiographic regions: the Kazan Uplands portion of the Canadian Shield and the Interior Plains. It was part of Glacial Lake McConnell in the pre-glacial valleys reshaped by erosional ice during the Pleistocene. Since, the lake has changed from post-glacial rebound following the ice melting. Precambrian rocks of the Canadian Shield form the eastern margin of the McTavish Arm. These rocks of the Precambrian are sedimentary and metamorphic deposits supplemented by igneous intrusions forming dikes and sills.

The oldest evidence of human habitation of Great Slave Lake is from about 6,000 BCE.

Lake Athabasca would not look like a great candidate except for its historic role as a part of historic Lake McConnell and Lake Peace.

Great Bear Lake, Great Slave Lake and Lake Athabasca are conventionally, collectively seen as remnants of Glacial Lake McConnell (all after the Younger Dryas), which in turn was formed from a smaller predecessor called Lake Peace.

Lake McConnell was a very large proglacial lake that existed in what is now Canada from 11,800 to 8,300 years ago. Other sources give starting and ending dates of about 12,000 and between 9,000 and 8,000 years ago respectively. It covered parts of what are now the Great Bear Lake, Great Slave Lake and Lake Athabaska basins up to an elevation of 280 m (920 ft) or 305 m (1,001 ft), with a maximum surface area of 210,000 km2 (81,000 sq mi) achieved 10,500 years ago. At its greatest length of 1,100 km (680 mi), it was longer than any modern freshwater lake. "Lake McConnell (or its smaller predecessor, Lake Peace) is believed to have drained first into Lake Agassiz", an even larger lake to the southeast, "then into the Arctic Ocean via the Mackenzie River, then back into Lake Agassiz, and then back to the Arctic Ocean" at various times in its history. Either 8,300 or between 9,000 and 8,000 years ago, it divided to form Great Slave Lake and Lake Athabaska. These two and Great Bear Lake are considered its 'daughter' lakes.

The Lake Peace route to North America only became passable after the Younger Dryas event (300 years later according to one study, at that very moment according to bison mtDNA).

So, the possibility that Lake Peace was a Younger Dryas impact crater is actually quite strong.