A river like no other
Posted on homepage: 1 March 2010 (GMT+10)
‘No possible action of any flood could thus have modelled the land, either within the valley or along the open coast.’1 So wrote Charles Darwin about the Santa Cruz River in southern Patagonia. He was in the third year of his Beagle voyage, having visited many locations along South America’s southeastern coast. He had identified step-like plains running inland from the sea, and he thought they were caused by the slow subsidence and elevation of the land over a very long time, with the receding sea repeatedly eroding the flat surfaces.
Exploring the river during April 1834, Darwin saw similar step-like plains on both sides and a layer of basalt, with very little basalt rubble downstream. He was convinced that the river had insufficient strength to erode such large volumes of basalt and grind the rubble to sand—it could only have been done by the sea.
He postulated an ancient sea strait cutting the entire continent from the Atlantic to the Pacific! Darwin concluded, ‘It makes the head almost giddy to reflect on the number of years, century after century, which the tides, unaided by a heavy surf, must have required to have corroded so vast an area and thickness of solid basaltic lava.’1 His mentor, Charles Lyell, was the one who largely introduced the ‘slow and gradual long ages’ concept to geology. Like him, Darwin totally rejected any sudden, catastrophic agency.
The Santa Cruz River
Rio Santa Cruz is an unusual river, flowing out of a lake (Lago Argentino) at a rate that could comfortably supply the water needs of 15 cities the size of New York.2,3 It snakes majestically across the Patagonian plain for 385 km (240 miles), with no tributaries.2
Thirty km (20 miles) at its widest, the river valley narrows through three steps to about 3 km (2 miles) at the bottom. However, the river is no wider than 200 m (700 ft) in most places. Such a river is called underfit, i.e. much smaller than the size of the valley it flows in. Darwin recorded a valley width of only 16 km (10 miles), indicating he never climbed to the top of the slope where the real width is clearly visible.
What if Darwin had travelled all the way to the river’s source: Lago Argentino? Presumably his astute mind and keen sense of observation would have led him to an explanation consistent with his view: Lago Argentino is also a remnant of an ancient arm of the sea. Ideally, he would have looked for a place at the lake’s westernmost end where his ancient straits were still visible as a deep cut across the Andes. If so, he would have been deeply disappointed to find, instead, a continuous mountain range from which the beautiful Perito Moreno glacier (pictured above) descends directly into the lake.
The Santa Cruz River and meltwater flooding
The water in Lago Argentino comes from the melting of the ice of the glaciers in the Los Glaciares National Park of which Perito Moreno is the most important. As the glacier advances into the lake, it sometimes separates it into two arms. Without drainage, meltwater in the southern arm sometimes rises 30 m (100 ft) behind the ice dam which it eventually breaches, releasing the water into the main lake. Such breaching has been recorded at least 19 times in the last 90 years.4 Further south, a small glacial lake disappeared overnight in 2007 because of a breached ice dam.5
During the final stages of the Ice Age,6 the Patagonian Ice Cap covered most of the Andes7 and at the end of the Ice Age, meltwater accumulated in lakes under the ice and at the edge of the ice cap. A much larger Lago Argentino formed, probably dammed towards the east by massive moraines and ice. When the dam breached, a first burst cut a more shallow channel over 30 km (20 miles) wide—the uppermost step. Then a second, deeper and narrower channel was cut which reached the basalt layer, undermining and eventually cutting it. The flow diminished until a river roughly the size of the present one remained.
The soft sediments could not preserve the usual landmarks such floods create. There are however silent witnesses strewn across the valley: rounded blocks, some very large, that display many scars of their collisions with other blocks as they were hurled downstream by the floodwaters. These differ from blocks carried by ice.
The meltwater flood hypothesis
Geologists today believe that glacial meltwater floods carved unusual landscapes like the Channeled Scablands in Washington State, USA. A larger flood in Canada drained Lake Agassiz’s glacial meltwater and cut the Niagara Escarpment and Gorge and the St Lawrence River. In Canada many floods also occurred underneath the ice sheet. In Alberta, a massive subglacial flood probably shaped most of the foothills and possibly the Rockies themselves.8
Catastrophic meltwater floods also cut the narrow land bridge connecting Europe with Britain—ironically the home of the father of anti-catastrophist geology, Charles Lyell.
The late Derek Ager, a British geologist and anti-creationist, wrote: ‘Just as politicians rewrite human history, so geologists rewrite earth history. For a century and a half the geological world has been dominated, one might even say brain-washed, by the gradualistic uniformitarianism of Charles Lyell. Any suggestion of “catastrophic” events has been rejected as old-fashioned, unscientific and even laughable.’9
Darwin and the glaciers
When Darwin left Europe in December 1831 on board the Beagle, the idea of ice ages was in its incipient stages. He did not fully understand the power of glaciers in eroding and transporting rocks, nor that glaciers extended far from the mountains in the recent past. He had already seen and recorded many erratic (i.e. glacier-transported) blocks on the surface of the South American Pampas but strongly believed, following Lyell, that they had been transported there by icebergs when the sea was covering the Pampas.
Darwin published his journal (The Voyage of the Beagle) in 1839, three years after his return to England. At that time he was perfectly aware of the scientific theory of ice ages put forward by the Swiss geologist, Louis Agassiz.10 In fact Lyell had openly opposed it in his presidential address to the Geological Society of London in 1836.11
Darwin himself wrote a passionate critique of Agassiz’s ice age theory.11 His aversion to it may have been aided by the fact that by that time he had started to think along evolutionary lines, whilst Agassiz, though a long-ager, was a staunch anti-evolutionist. As we all know today, Agassiz was right about glaciers and the Ice Age; Darwin was wrong.
Darwin’s Beagle voyage, in addition to his basic geological training and Lyell’s book, Principles of Geology, made him an experienced field geologist. Exploring the Santa Cruz River played an important role in developing Darwin’s geological views. It reinforced his belief in deep geological time—and, as few scholars today doubt, this played a key part in shaping his evolutionary ideas in biology.11
Yet most of his interpretations of this area (and many others in South America) were erroneous, according to modern geology. He assumed for instance that the entire valley of the Santa Cruz River was once an arm of the sea. But it is believed today that it was most probably cut by catastrophic meltwater flooding towards the end of the Ice Age, a concept which Darwin opposed.12
The slow, uniform flow of time and geological processes that Darwin believed in is now replaced by a new paradigm according to which most geological processes occurred rather suddenly, often as catastrophic events. Though the Genesis Flood is still utterly rejected by the evolutionary establishment—despite the massive evidence—it was the most important catastrophe of all. If a sudden burst of meltwater coming from melting glaciers could cut the enormous Santa Cruz valley so quickly, how much more would the global Flood, involving all the water in the oceans, have done in terms of shaping the land?
References and notes
- Darwin, C., The Origin of Species and the Voyage of the Beagle, Alfred A. Knopf, New York, London, Toronto, p. 193, 2003. Return to text.
- Santa Cruz River (Argentina) <en.wikipedia.org/wiki/Santa_Cruz_River,_Argentina>, 16 June 2008. Return to text.
- Environmental issues in New York City, <en.wikipedia.org/wiki/Environmental_issues_in_New_York_City#Water_supply> based on 2006 figures. Return to text.
- Perito Moreno Glacier, <en.wikipedia.org/wiki/Perito_Moreno_Glacier>, 16 June 2008. Return to text.
- Chilean Lake disappears, Earth Observatory, <earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17700>, 16 June 2008. Return to text.
- There is much evidence for an Ice Age triggered by, and straight after, the Genesis Flood. See <creation.com/ice>. Return to text.
- Thompson, L.G., Moselley-Thompson, E. and Henderson, K.A., Ice-core paleoclimate records in tropical South America since the Last Glacial Maximum, Journal of Quaternary Science, 15(4):377–394, 2000. Return to text.
- Silvestru, E., Wild, wild floods, Journal of Creation 22(1):12–14, 2008. Return to text.
- Ager, D., The New Catastrophism: the importance of the rare event in geological history, Cambridge University Press, Cambridge, p. xi, 1993. Return to text.
- Louis Agassiz, <en.wikipedia.org/wiki/Louis_Agassiz>, 16 June 2008. The idea of glaciers beyond the Alps was first proposed in 1821 by Venetz and further confirmed by de Carpentier, both Swiss. Return to text.
- Herbert, S., Charles Darwin, geologist, Cornell University Press, Ithaca and London, p. 255, 2005. Return to text.
- A shallow sea covered most of Southern Patagonia but the marine erosion did little, mostly flattening the top layers of sediments. It is thought that the sea temporarily invaded the land due to a sudden input of large amounts of fresh water from the land. Return to text.