Prehistoric Transoceanic Navigation into America

Icame across a very interesting paper today, its title is revealing: Modelling pre-historic transoceanic crossings into the Americas (Alvaro Montenegro, Reneé Hetherington, Michael Eby, and Andrew J. Weaver. Quaternary Science Reviews, Vol, 25, Issues 11–12, June 2006, pp. 1323-1338 https://doi.org/10.1016/j.quascirev.2005.11.008, 🔒), and it explores the time it would have taken pre-Hispanic navigators to reach the New World from Europe, Asia, Africa and Oceania.

The abstract summarizes this notion as follows:

"A method for simulating vessel movement in an oceanic setting is described and used to provide temporal and spatial constraints to potential pre-historic transoceanic crossings into the Americas. The technique is based on current and wind output from numerical models and on leeway drift estimates from the United States Coast Guard. Simulations were carried out for present day (PD) and last glacial maximum (LGM) wind and current conditions. The fastest crossing time for the PD no-paddling experiments occurs between Australia and New Zealand in 23 days. The fastest transoceanic crossings occur between Central Europe and Iceland/Greenland in 72 days, Japan and North America in 83 days and northern Africa and South America in 91 days. The crossing with the highest probabilities of occurrence under 180 days occurs between southern Africa and South America (13%). This increases to 18% when paddling is allowed. Crossings from northern Africa to South America, from Australia to New Zealand and from New Zealand to South America have probabilities of occurrence ≥5%. Differences between LGM and PD crossing times and rates of occurrence range between 25% and 30%, indicating that the PD results serve as a rough estimate of LGM crossings. Mid-latitude crossings are of shorter duration and more probable during the LGM."

It is interesting to see that the NZ to South America transpacific crossing has chances higher than 5%, yet, it is lower than the 13% to 18% probability for a South Africa to South America crossing.

Another paper I found (Royer, T.C., and B. Finney. 2020. An oceanographic perspective on early human migrations to the Americas. Oceanography 33(1):32–41, https://doi.org/10.5670/oceanog.2020.102. 🔓) investigates the navigation of the North Pacific during the period that is now recognized as the peopling-window from Asia into NW America. Of course it only contemplates the end of the last Ice Age, and the LGM, but its analyisis is sound from a geoscience point of view, even if I disagree with the timeline it takes from anthropologists and archaeologists.

This paper "on the roles that oceanographic conditions played in initially helping and later hindering these early marine travels to the Americas.", and asks about the currents, boat technology, haul-outs and stopping points, and also something I hadn't heard about before, "forebulging".

Forebulges

I was familiar with isostatic rebound, when the ice of the glaciers melted, the enormous weight of the ice sheet vanished, and the continent rose like a cork floating on the undelying mantle. This was almost immediate following deglaciation, but the process still continues at roughly 1 cm per year uplift (roughly 0.4 in per year).

Forebulges is the reaction of the Earth's crust to an advancing ice sheet. As the weight of the ic pushes down the crust beneath, the crust in front of the ice sheet rises, uplifted and bulging. This could have made the land around the frontal area of the ice sheet rise by more than 100 meters (330 ft.). The seafloor could have risen even more than the lower sea levels caused by the Ice Age (which locked up millions of gallons of water as ice, on top of the continents).

Glacial rebound and forebulge. Source

The paper's remark that "...recognizing that sea level was at least 120 m lower than it is now, combined with a possible uplift of the seafloor, allows that there could have been sufficient areas of dry land available for island-hopping mariners in skin boats to transit the coastline of Alaska and British Columbia at about 16,000 yr BP." This is interesting, because skin boats are flimsy and not suitable for long open sea voyages, and also because these same conditions would have existed in any of the previous Glacial Maximums, and could have been used by sailors to cross from Asia to the West Coast of North America.

The glacial maximums correspond with the even-numbered Marine Isotope Stages or MIS:

• MIS 2: The Last Glacial Maximum (LGM), which peaked around 22,000 years ago
• MIS 4: Started ~71,000 years ago.
• MIS 6: or the Penultimate Glacial Period, started ~191,000 years ago.
• MIS 8: Started ~300,000 years ago, when we believe the first Homo sapiens appeared in Africa. Before this date we only had Neanderthals and possibly Denisovans.
• MIS 10: Started approx. 374,000 years ago.
• MIS 12: Started some 478,000 years ago.
• MIS 14: Started around 563,000 years ago.
• MIS 16: Started ~676,000 years ago.
• MIS 18: Started about 761,000 years ago.
• MIS 20: Started ~814,000 years ago.

The analysis mentions that after 15.000 years ago, it would have been more difficult for those sailing from Asia, to reach America due to rising sea levels, and stronger counter currents (east-to-west). Only after deglaciation did the current coastal islands appear along the coast of Alaska and Canada allowing new arrivals some 11.300 years ago. This is interesting! It could indicate why there were differnt peopling pulses into America, and also the reason for some back migrations into Siberia.

The paper also gives an idea on the rapid changes of that time: "A hiatus in the use of this eastward and southward waterway probably lasted for several thousand years, prohibiting new settlers to the Americas but allowing northward passage back to Beringia. It seems likely that early migrants to the Americas were victims of a severe climate change when sea levels rose at 40–50 mm yr–1 for 340 years, more than an order of magnitude greater than our present-day sea level rise of about 3 mm yr–1."

Again, this would have happened during any of the previous deglaciation events.

Finally, it suggests some actions that could help learn more about this matter:

• Do shell middens, stone fish weirs, and structures exist beneath meters of glacial sediments, particularly within submerged flow channels?
• Can sub-bottom seismic profiling and coring be used as effective tools to investigate for possible prehistoric underwater archaeology features (e.g., Dixon and Monteleone, 2014)?
• Can local sea level curves, elevational models, and archaeological site prediction models be used to locate subaerial coastal sites documenting early human occupation (e.g., McLaren et al., 2019)?

I really like the pragmatic attitude of earth-science scholars, more concrete than the findings of those studying DNA (less algorithms and computer models, and more "real" data).

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

Homo Heidelbergensis lived in Glacial Britain 712 to 424 ky ago

Our distant relatives and ancestors managed to survive in the icy and frozen wastelands of northern Britain 712 to 424 kya according to a paper published on Sep. 1, 2025.

These people were not Homo sapiens they were Homo heidelbergensis which we believe are the stock from which Neanderthals, Denisovans, and we originated from.

Read the article: Key, A., Clark, J., Lauer, T. et al. Hominin glacial-stage occupation 712,000 to 424,000 years ago at Fordwich Pit, Old Park (Canterbury, UK). Nat Ecol Evol (2025). https://doi.org/10.1038/s41559-025-02829-x

The site reveals that these people were well adapted to living in cold places. They also found tools of different people. The early occupants of the site lived there between 773 and 607 ky and used acheulean tools (first developed by H. erectus). This period was cold. This is "evidence of the earliest known Acheulean bifaces in northern Europe". Ths site was inhabited again some two hundred thousand years later (420 ky) by another group of hominins that also used Acheulean tools.

The paper stresses the fact that this site "provides evidence for Lower Palaeolithic hominins [and] early human presence above 51° latitude during a glacial stage and handaxe production in northern Europe from MIS 17 to 16".

The paper states that these people "could, therefore, have had the cultural and technological attributes necessary to survive in these cooler climates and ecologies." The authors reckon that they occupied this area during a cold but not glacial period, when there were grasslands and grazing animals in the area. Yet they don't rule out habitation during a colder period either, the evidence hints at a "potentially summer-only occupation and even ice-proximal conditions." At that time, the glacial front was only 65 km north of the site. Walls of ice marked the limit of habitability. There is little evidence of trees in the area and the plants recovered from the site suggest it was similar to the Siberian steppe.

However, the oldest evidence for controlled fire in Europe is more recent, some 300 to 400 thousand years ago. We don't know if these people in Britain used fire. Did they burn dung in the absence of wood? or did they burn bones? In any case, it shows that people with less cranial capacity than modern humans or our more recent relatives, the Neanderthals and Denisovans, could cope with cold, icy climates and survive. This means that they could have done the same in Northeastern Asia (Northern China, Manchuria, and Siberia) on their way into America at any time between 700 and 400 ky.

CAPTION HERE. Copyright © 2025 by Austin Whittall

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

Patagonia during the Last Ice Age

Glaciers covered the Andean region, and part of the Patagonian steppe during the Ice Ages that took place over the past 2 million years. The remaining Ice Field are minute in comparison to the ice sheets that the first natives, the Paleo-Indians encountered when they reached the area around 20,000 years ago.

I found an Excellent interactive map online (see it online here) ) that shows how the ice fields evolved as they melted, the glacial lakes they formed, and how the Patagonian coasline changed as sea levels rose. Below are two still from the animated map showing the panorama 35 and 15 kya.

Ice sheets over the years. Source: Patice

It is interesting to point out that the Patagonian sea shelf covered a vast aerea (now submerged) covering around 180,000 km² (70,000 sq. mi.). Sea levels were roughtly 120 m (395 ft) lower than current levels, and the shelf would have been on average, 170 km wide (110 mi.) This was a unique ecological niche for the first Patagonians to hunt, gather, and live on. The megafauna and forests would have extended eastwards along what is now the steppe region more in this paper).

The Ice Fields nowadays

Below are some pictures of the remaining Ice Fields. The Southern Ice Field ranks third globally in size after the Antarctic and Greenland. But, declining due to climate change.

North Patagonian Ice Field, seen from space. Looking West. It is 125 km (78 mi.) long.

South Patagonian Ice Field, seen from space. From left to right Lakes Argentino, Viedma, San Martin, Cardiel in Argentina. Far left lakes in the Torres del Paine Nat. Park, Chile . Looking West. It is 350 km (220 mi.) long.

Mount Fitz Roy and a part of the South Patagonian Ice Field

Monte Sarmiento in the Darwin Ice Field, Tierra del Fuego.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

Pendejo Cave: humans in America 55,000 years ago?

Pendejo Cave in New Mexico has produced some interesting evidence of an early migration into America. The book I browsed online (Pendejo Cave, Richard S. MacNeish, Jane G. Liddy UNM Press, 2003) has plenty of information.

It was excavated by MacNeish between February 1990 and April 1992. He found evidence of Pre-Clovis occupation and figures of up to 50,000 years BP were given at that time.

First a trivial remark. "Pendejo" (Pen-Day-Hoe) in Spanish means "pubic hair" and is used as a derogatory term equivalent to "idiot", "kid", "jerk", etc. Why was the cave given this name, is a mystery.

But let's get back to the science. Here several things were found:

• Palm prints on baked clay 12-37Ky BP (source)
• Human hairs 19,500 years old with DNA that did not correspond to the "four primary clusters" of Native American DNA (page 428).
• A buffalo bone 35,000 years with chips caused by human workmanship (source)
• The "heel bone" of a horse species which is now extinct, with a stone wedge jammed into it, 36,000 years old (source and photo)

The cave is shown below:

The book also includes several maps showing how the humans spread across the Americas from Beringia, but long before the currently accepted dates. Below is one image (I liked the lower left "sea level" swings during the different glacial and interglacial periods, as it shows several windows during which humans could have reached America earlier than 15 to 20 Kya and the purported Beringian standstill).

One of the book's maps

McNeish proposed a very early arrival date for Humans in America (58,000 to 70,000 years ago), below is an excerpt from the book (page 486) where he mentions it:

It mentions the "pebble tools" (Orogrande tool complex) such as those found in the cave and shown in the map above.

The coarse tools are used by those who question McNeish's findings because they dismiss them as too crude or even as geofacts (not man made).

However Homo habilis made very coarse tools ("Oldowan" pebble tools and choppers), so maybe the Pendejo Cave people were not even Homo sapiens.

As expected the dates were questioned by those who object an early migration into the New World. McNeish passed away in 2001, but his work has survived.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2020 by Austin Whittall © 

Beringia the modern "Lemuria"

As orthodox science accepts as proven fact that the Americas were peopled by a very limited group of people in a rapid expansion that spanned the continent from Alaska to Tierra del Fuego in a few milennia, they are now building "proof" to support this notion.

The proof is known as the "Beringian standstill hypothesis". It involves a Twentyfirst century lost continent, which is not Atlantis (the mythical land that sunk in the Atlantic Ocean) but "Beringia", a rehash of the legendary continent of "Lemuria" or "Mu", which were invented as dry land stepping stones before plate tectonics correctly explained how trees and animals managed to cross vast oceans and people distant lands.

In a nutshell, a recent paper ("Out of Beringia?" [3]) elaborates on a theory originally suggested by Eric Hultén in 1937 [4]: that the Bering Strait land bridge was a refugia for tundra vegetation during the Ice Ages. The paper's authors, Hoffecker, Elias and O'Rourke contend that apart from tundra plants, Beringia was also "a glacial refugium and postglacial center of dispersal for the people who first settled the Americas" [3].

They believe that the ancestors of Amerindians split from their Asian relatives 25 kya, lived in Beringia for about 10,000 years and moved into America when the glaciers began melting and apart flooding Beringia, opened up the routes into the heart of America.

The 10 kya standstill arises because the distinct American Native mtDNA requires an isolation of several thousand years in isolation. The paper believes that it was possible because the tundra also supported some stunted trees (birch, adler, willow) which could have been used to ignite and burn megafaunal bones and give off plenty of heat. The land bridge also supported an edible fauna of mammoths, elk, moose and bison.

The New Lemuria

The lost continent of Lemuria or Mu.

Beringia during the last Ice Age. From [2]

The new Lemuria (or Beringian Standstill hypothesis) arises to be able to explain how the "American founding fathers", ancestral to all Native Americans, managed to mutate their Asian mtDNA into novel haplotypes, develop new alleles that were distinct from the original Asian stock and then disperse across America without any of these genetic traces remaining back in Asia.

The fact is that there are mtDNA haplogroups found exclusively in America but not in Asia (A2, B2, C1b, C1c, C1d, D1 and D4h3). This pan-american uniqueness also extends to Y chromosome haplogroup Q1a3a-M3 and to some privatee alleles (i.e. autosomal 9-repeat at the microsatellite locus D9S 1120).

If they are not found in Asia, then, the obvious and most parsimonious answer is that they originated in America, and dispersed across the continent, but no, orthodoxy does not accept this, and had to invent a "Moses-like" band of migrants wandering in the wilderness. But instead of 40 years, these people spent 10,000 years in their Beringian "Sinai" before reaching the "Promised Land" of America.

The justification for the "Standstill" is the following:

1. Large ice sheets blocked access into America until about 15,000 years ago.
2. An earlier date (i.e. older than 15 kya) for the peopling of America is not acceptable for orthodox science.
3. Modern humans are believed to have reached Eastern Asia 25,000 years ago, but did not move into America then (due to 1 and 2. above)
4. mtDNA had to diversify into American haplogroups, which takes time (10 ky is sufficient).
5. But diversification had to happen in isolation (to avoid any of it remaining in Asia).
6. The only place this could happen: in between Asia and America: Beringia.

So we imagine a vast land with cold but bearable climate, cut off from Asia and America by ice fields that could not be crossed by men. And a group of humans isolated there for 10 ky, until the Alaskan gateways opened (I wonder why the Siberian one reamained closed... The mechanism is not explained. But it is necessary to avoid any of those distinct genetic markers from going back into Asia). Of course, since the oldest Paleoindian sites acceptable for orthodoxy are about 15 kya, (some are in South America), so this means that the peopling of the continent had to take place super fast. This means that these people who sat around Beringia for 10,000 years suddenly rushed across the New World and settled it immediately.

The map below summarizes it (source: wikipedia).

This is a bit too far fetched for my liking.

The Second Wave

Then, after this initial wave of Paleoindians, a second wave marched across Beringia from Eastern Siberia: the ancestors of those bearing hablogroups A2a, A2b, D2a, D3 and X2a, which are found in the north of North America, which by the way have similarities with Eastern Asian groups and share common languages.

However, there is a problem with the language question see my post on American Languages), which another recent paper has also attributed to a "Beringian isolation" (it is in vogue now), but different from the one in the paper mentioned above.

This paper uses phylogenetic methods to support the theory that the American Na Dene and the SiberianYeniseian languages connection is very probably due to a "radiation out of Beringia with back-migration into central Asia than a migration from central or western Asia to North America". [1]

So here we have another group in Beringia that moves both back into Asia and ahead, into North America. Which is almost simultaneous with the one mentioned above! So why didn't the genes follow the languages back into Asia? Also, it argues for an older initial population of America (15-40 kya) which predates the one mentioned above. Please allow me to quote the paper extensively (bold is mine):

"DNA evidence supports at least three migrations with the earliest 15–40,000 BP referred to generically as the Paleoindian and associated with the greatest distribution of language and cultural groups across North, Meso, and South America; the second 12–14,000 BP is the Na-Dene distributed in North America from Alaska to the Pacific Northwest and from Canada to the U.S. Southwest; and the third ca. 9000 BP is Eskimo-Aleut with circumpolar distribution.
Linguists have classified Eskimo-Aleut and Na-Dene as separate language stocks, and the rest of the languages of the Americas as belonging to numerous stocks, but have otherwise been mostly silent on questions that connect Asian and the American populations because, with the exception of Eskimo-Aleut, the dates of these earlier connections lie beyond the traditionally accepted limit for comparative reconstruction.
Linguistic claims of more distant relationships have relied instead on the more controversial method of mass (or multilateral) comparison of lexical items subjectively judged as similar. Using such methods a Dene-Yeniseian (DY) connection linking Asia to North America has been suggested for nearly 100 years, but only recently has a stronger case been made using methods of linguistic reconstruction, which has been peer reviewed with cautious optimism urging alternative methods for its evaluation. The hypothesis of a DY language family prompted claims of proof for the origin of Native Americans in central or western Asia, the relationship fitting into a popular narrative for the peopling of the Americas.
[...]
Our results support an argument that, if the Dene-Yeniseian connection is true, it more likely reflects radiation out of Beringia with both eastward migrations into North America and westward migration into Asia rather than a unidirectional migration from Asia to North America." [1]

The language flow (and the people speaking them) is bidirectional, 12-14kya and only corresponds to North American Na-Dene natives, while the other paper covers a unidirectional flow (into America), across the whole continent, 15 kya.

The theories are in conflict and should be compatibilized.

Beringia

Let's take a look at the scene where these events took place:

The Beringian land bridge is currently submerged and only appeared when the glaciers accumulated enough water (as ice) to drop sea levels. This happened during the Ice Ages of the Pleistocene, and also earlier.

We know that it existed for about 10 ky between (roughly) 32 and 18 kya. It was narrow in its central part (current Bering Strait region) it was however wide at its oriental and occidental portions. It covered an area larger than the state of Texas [2].

The extreme dryness of the area did not allow snow to accumulate and build up glacers so it remained ice free, glaciation surrounded it, in the mountains in alaska and Siberia but not in the lowlands of Yukon, Alaska, Eastern Siberia and, of course, Beringia. These remained free of ice during the Pleistocene.

The period during which this "standstill" took place, the Last Glacial Maximum (LGM), was "relatively dry and cold with cooler summers" [2].

Closing Comments

Perhaps the refugium applies to the Na-Dene speakers, late arrivals to the continent. But the Paleoindians definitively reached America over 30 kya. Future findings and older sites will confirm this hunch.

Land Bridges formed across Bering Strait many times during the past 1,500,000 years and were contemporary to hominds who could have marched across them: H. erectus, Neanderthals and even archaic Modern Humans from Asia.

I am surprised at the persistence of notions such as "a late peopling of America" and patches to try to justify the holes in the theory instead of building a new one that explains all facts.

Sources

[1] Mark A. Sicoli and Gary Holton, (2014). Linguistic Phylogenies Support Back-Migration from Beringia to Asia. March 12, 2014DOI: 10.1371/journal.pone.0091722
[2] S A Elias and J Brigham-Grette, (2013). Late Pleistocene Glacial Events in Beringia From: Encyclopedia of Quaternary Science, 2, (2013) 191-201. doi:10.1016/B978-0-444-53643-3.00116-3. pp +191
[3] John F. Hoffecker, Scott A. Elias and Dennis H. O'Rourke, (2014). Out of Beringia?. Science, vol. 343, no. 6174, pp. 979-980; doi: 10.1126/science.1250768

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2014 by Austin Whittall © 

The South African "out of Africa" route

My last posts have dealt with a Brazilian geologist and Archaeologist, Maria Beltrão. She has proposed that our distant relative, the H. erectus reached America over 1 million years ago. Below I post about her and the route she proposes for this migration of H. erectus into America.

Beltrão writes about herself

Beltrão points out in an article [1] that hominids have been living in Asia at least since 1.8 million years ago (in Indonesia, central China and Pakistan), and also in Georgia, (the remains are probably anHomo habilis), with this in mind, she adds:

“If over 5 million years ago, animals crossed from Asia to America and vice versa, man, being a hunter why did he say “no” to America and did not follow his prey during the last 2 or 4 million years?”[1]

As a geologist, she has sought out sites whose surface is sealed off, either with marl as at Toca da Esperança, or with lava as at Itaboraí, to ensure undisturbed layers.

The South African gateway

She proposed (together with Paepe, 1978 - I have not been able to find the paper / article) a migration from South Africa to South America during the glacial period, crossing the ice pack.

This is an interesting “Out of Africa” route, it must go south, cross the sea between South Africa and the ice pack surrounding the Antarctic, then go along the pack’s coastline till it reaches America and from there, back up, into Patagonia. A long and risky journey that combines sailing and trekking along the ice pack.

I have posted about a possible route via the Antarctic into South America, but from the West, from Australia, New Zealand and Tasmania. An equally difficult and longer route than the South African one.

To get an idea of what would have to be trekked – sailed – navigated, I combined two different maps that depict the coastline of Southern Africa and the Southern part of South America during the Last Glacial Maximum (LGM), when most of the water was stashed away in the form of gigantic ice sheets covering the Northern Hemisphere, Antarctica and parts of South America and New Zealand. The sea level dropped and exposed parts of the continental shelves of both continents (shaded in light green). The sources of the maps are [2] and [3]. I also added another map taken from[4], and adapted from its FIG. 5. Which shows the ice thickness in meters (filled color contours) winter during the LGM. South Africa not included in the original map, was added by me. The red arrow shows the possible land and sea route that could be used to reach America from Africa.

I am well aware that our friend, the H. erectus would have reached America long before the last Ice Age and its LGM, yet even so, I chose the LGM coastline for two reasons: one, that all previous glaciations would have provoked a similar drop in sea level and, two, that I could not find any data on previous glaciation coastlines.

Below are the maps:

Maps showing Antarctic route from South Africa to America. LGM coastline given as a reference. Adapted by A. Whittall from [2][3] and [4]

I believe that the circumpolar current flows from West to East and therefore would hinder a direct navigation across the South Atlantic. But I must check to see if this is valid for glacial periods.

Sources

[1] Maria Beltrão, (2008). Depoimentos de Arqueólogos pioneiros: Maria Beltrão, ISSN 1807-1783, atualizado em 02 de abril de 2008. História e-História

[2] C.Leigh Broadhursta et al, (2002). Brain-specific lipids from marine, lacustrine, or terrestrial food resources: potential impact on early African Homo sapiens . Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. Volume 131, Issue 4, April 2002, Pages 653–673

[3] L. Miotti and M.C. Salemme, (2003), When Patagonia was colonized: people mobility at high latitudes during Pleistocene/Holocene transition. Quaternary International. Volumes 109–110, 2003, Pages 95–111

[4] Otto-Bliesner, et al, (2006). Last Glacial Maximum and Holocene Climate in CCSM3 J. Climate, 19, 2526–2544. doi: http://dx.doi.org/10.1175/JCLI3748.1

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2012 by Austin Whittall © 

Lake Monsters - The origin of their habitat. Part 1

 

If the Patagonian lakes are home to lake “monsters” and mysterious creatures, we can learn more about these cryptids if we study the lakes themselves and their origin.

Patagonian lakes, both in Argentina and Chile are mostly located along the Andes mountain ranges which run in a north-south direction and are cut on an east-west direction by many valleys, some of which are filled with deep freshwater lakes. A few exceptions are lakes set in the steppe (i.e. Lake Colhue Huapi – which is fed by water from the Andean snow melt) some of which lake drainage and are fed by the scarce rainfall.

These Andean lakes were carved by the glaciers during the Ice Ages.

Ice Ages and the formation of lakes

Sixteen different “Ice Ages” have been recorded in the southern tipo of Patagonian mainland during the last 2 million years, and at least six in Tierra del Fuego Island during the last million years.[1]

The most severe of these was the “GGP” or Gran Glaciación Patagónica (Great Patagonian Glaciation), about 1 million years ago. During this event, the ice sheets reached the Atlantic Ocean at the area of the Strait of Magellan. Later glacier advances extended for several hundred kilometers but did not reach the sea (i.e up to 300 km in Tierra del Fuego). [1]

All of Patagonia is strewn with rounded boulders and pebbles created by the glaciers and their melt waters.

The last glacial event began about 25,000 years ago and most of southern Patagonia was covered with glaciers or a frozen tundra with permafrost. Only on certain warmer spots along the sea shore did the Nothofagus forest survive.[1]

Below are some maps showing the areas that were covered by the ice sheets:

Northern Patagonia. From the Internet [*]
The striped area was covered by glaciers. The dotted red line is the border between Chile and Argentina.

Northern Patagonia coverage, detail. From the Internet [*]
In gray the icefields, in black, current glaciers. Arrows show the direction of the ice sheet flow.

Southern Patagonia Ice coverage- note extant icefields in green. From [3].

Ice starts to melt: paleolakes

After deglaciation, the forests retreated together with the glaciers, their source of water, to occupy their current habitat in the Andes, leaving the now arid Patagonian plateau to shrubs and dwarfish bushes (a dry steppe).

During the ice ages, the glaciers and their moraines formed large natural dams that contained what are known as paleolakes. These large bodies of water had very high water levels and drained towards the Atlantic Ocean. The wide and deep valleys that cross the Patagonian steppe from west to east witness the might of the rivers that drained these lakes. Now most of these valleys hold small rivers (i.e. rivers Chico, Coyle, Gallegos) and some even run dry before reaching the coast (i.e. Deseado River).

During the late Pleistocene epoch (between 13,200 and 7,800 years ago), climate grew warmer and the glaciers began melting. This changed not only the weather and local ecology, but also affected the landscape as the paleolakes fragmented into smaller ones and their water level dropped, in some cases below the eastern terminal moraines, blocking their outflow into the Atlantic Ocean, and causing them to empty westwards into the Pacific Ocean.[2]

These paleo lakes were, from north to south, the following [2]

Elpalafquen 41° S. Was a vast lake system that drained through the Limay River into the Atlantic (which still drains many lakes of the eastern slope of the Andes such as Nahuel Huapi, Espejo, Correntoso, Gutiérrez, Moreno, Traful, etc.) it broke up about 13,200 years ago and some lakes began draining into the South Pacific through the Manso River (such as Mascardi, Steffen, Fonck, Guglielmo, Césares, Hess, etc.).

Caldenius 47-48° S, included current lakes Azara, Belgrano, Mogote, Nansen, Volcán and Burmeister, all of which are now part of the Argentine Perito Moreno National Park. It drained into the Atlantic until ten thousand years ago when it also began to drain through a channel cut through the Andes. Its level was over 100 m (300 ft.) higher than the current water level of Lake Belgrano.

Fuegian paleolake 54-55° S, began melting 7,800 years ago. It comprised lakes Fagnano, Yehuin and Chepelmut as well as the Esperanza bog. Nowadays only Esperanza drains towards the Atlantic through the del Fuego River. The other three lakes drain into the Strait of Magellan.

Remnant glaciers

All that remains of these imposing glaciers that once covered a very large surface of Patagonia are two continental ice sheets covering an area of 21,000 km2 (8,110 sq. mi.). These are the third biggest extensions of continental ice after Antarctica and Greenland. Located roughly 73°W and between 47° and 51°30’ S they are fed by the abundant winter snowfall and maintained by frost most of the year; however, they are now imperiled by climate change as can be seen in the following photographs of Upsala Glacier (Southern Icefield), comparing the same view in 1928 and 2004:

Upsala Glacier (49°50' S, 73°17'W) has a surface area of 870 km² (340 sq.mi.) and a length of about 60 km (37 mi.), making it the third largest Southern Hemisphere glacier outside Antarctica,and South America's longest glacier. It is shrinking rapidly. See Fig. 53 [3] which shows a map with the retreating front of this glacier (1968-1995).

See my photograph of the glacier in my post Here.

Northern Patagonian Icefield (47°00’S, 73°39’W) is about 120 km long (74 mi.) and 40-60 km wide (25 – 37 mi.) and covers an area of 4,200 km² (1,640 sq. mi.), capping the Andes.

Southern Patagonian Icefield (between 48°50’S and 51°30’S is about 40 km wide and covers a larger area (13,200 km², about 5,150 sq.mi.). This is the largest mass of ice outside of the Antarctic.

The remaining glaciers are distributed along the tall Andean peaks in smaller icefields, the larges of them is on Tierra del Fuego Island and has a surface area of about 2,500 km² (975 sq.mi.) it straddles Darwin Cordillera and Mount Sarmiento.

Impact on cryptids

From the above we can see that there were no lakes before the Ice Ages (2 million years ago max.). They must have been excavated in a gradual process, by which each successive glaciation dug deeper trough shaped valleys which during the warmer inter-glacial periods filled with water. And were repeatedly filled up again with ice sheets hundreds of meters thick during each new glacial period.

This must have exterminated any animals attempting to colonize these lakes until the last deglaciation some 10,000 years ago.

The current lakes are the remnants of gigantic paleolakes that broke up and split, shedding their water into both oceans. Their fauna prior to the introduction of salmonids in the 1900s was the local endemic Patagonian species, which hitch-hiked their way from lake to lake perhaps on the feet or feathers of the local water fowl.

This excludes the existence of any large "non-fish" freshwater creatures such as plesiosaurs and so on.

Large tropical mammals could have moved into the now arid Patagonia, but if they were aquatic creatures accustomed to the warmer and more humid conditions prevailing to the north of Patagonia, we must identify how they crossed the dry barren areas that now separate the Patagonian Andean forests from these northern tropical areas.

That is what we will do in our next post Here.

Bibliography.

[1] Coronato, A., Borromei, A., and Rabassa, J. Paleoclimas y Paleoescenarios en la Patagonia Austral y en Tierra del Fuego durante el Cuaternario.
[2] Del Valle, R., Tatur, A., and Rinaldi, C., Cambios en lagos y circulación fluvial vinculados al calentamiento climático del Pleistoceno Tardío-Holoceno Temprano en Patagonia e Isla 25 de Mayo, Islas Shetland del Sur, Antártida. Revista de la Asociación Geológica Argentina 62 (4): 618- 626 (2007)
[3] USGS. Historic Fluctuations of Outlet Glaciers from the Patagonian Ice Fields. Fig. 54.

Further Reading:

Glasser, N., Harrison, S., Winchester, V., and Aniya, M. Late Pleistocene and Holocene palaeoclimate and glacier fluctuations in Patagonia . Global and Planetary Change, Volume 43, Issues 1-2, August 2004, Pages 79-101.



Copyright 2009 by Austin Whittall ©

Patagonian Monsters