Sunday, February 3, 2013

An Early Description of Permafrost


At the beginning of the Nineteenth Century, permafrost was a very strange idea to European scientists. The word wouldn't be coined until 1943. The earliest descriptions from the century before were simply of frozen ground running deeper than it should. The idea was completely alien to anything they understood. If the ground was deeply frozen, how could trees grow? Any mining engineer could tell you that it gets hotter as you go down, not cooler. No, they determined, deeply frozen ground was just a myth of superstitious natives.

In 1806, while traveling on the Arctic coast near the Lena delta, Mikhail Adams made some passing references to permafrost that included, as far as I can tell, the first short descriptions of ice wedges and patterned ground. Adams came to the coast attempting to recover a frozen mammoth. Prior to his trip, fewer than a half-dozen mammoth carcasses had been described and one woolly rhinoceros had been recovered. None of these descriptions described them as being frozen, only buried. Adams, in describing his mammoth specifically went into the fact that it had first been sighted in frozen soil. While at the discovery site, he made some casual observations of the place where it was found that included more details than simply stating that the ground was frozen.

First, a few words about permafrost. Permafrost is much more that frozen mud with a foot or so of mushy mosquito maternity wards (tundra) on top, though that's what it mostly is. It's actually a very complex geological phenomenon that still isn't completely understood. Permafrost can contain walls of almost pure ice (ice wedges), mysterious round hills that look like burial mounds (pingos), thousands of small oval ponds that appear and disappear (thermokarst lakes), and rings on gravel beaches and mile after mile of honeycomb patterns on the ground (patterned ground).

Patterned ground is caused by ice wedges. Very simply put, cracks form in permafrost in polygonal patterns similar to cracks in dried up lakebeds during a drought  The case is different but the appearance is the same and the permafrost patterns are much larger. During the summer, melt water fills the cracks. The next winter, the ice expands, as ice will and that widens the crack. The next summer more water can get in, which widens the crack even more. Repeat for a few decades and the permafrost will be thoroughly broken up into a pattern. Because the ice wedge also expands upward, it will create the rice paddy pattern below (Fig. 1). Later in the summer, when the wedge has melted some, the pattern will be the exact opposite with the cracks being lower than the permafrost blocks.

 Fig. 1. Patterned ground. Source.

Back to Adams. The place where Adams recovered his mammoth was a bluff overlooking the sea. Rather than looking at the permafrost through a hole dug into it from above, he has able to see a huge slice of it. The bluff he looked at was well over a hundred feet tall and several miles long. The mammoth had eroded out of a relatively high point on the bluff and tumbled to the beach. While waiting the boat that would take him and his mammoth back to civilization, Adams climbed the bluff to a place near where the mammoth had first appeared. He described it thusly: 
Sa substance est une glace claire pure et d'un goût piquant, elle s'incline vers la mer, sa cime est couverte d'une couche de mousse et de terre friable d'une demie archine d'épaisseur. 
My translation of this is: 
Its substance is pure clear ice and has a pungent taste, it leans towards the sea, its top is covered with a layer of moss and soft earth half an archine thick [14 inches]. 
Two different English translations were published, essentially identical to mine. This passage caused some confusion for Nineteenth Century scientists. All other mammoth carcasses discovered in that century were found in frozen mud, not clear ice. Furthermore, the expeditions that visited the site found only mud. They chalked it up to the fact that Adams was a bit flaky and, outside his field, he was botanist, his work was rather sloppy. However, the existence of ice wedges might redeem Adams' reputation. At least, in this instance.

It just happens that Mamontovy Khayata, the place where the mammoth was found, has been the site of a joint German/Russian permafrost research project for the last twenty years. The picture below (Fig. 2.) is of the bluff in 2002. The light section of the bluff is a section of ice wedge. Beyond it is muddy permafrost and beyond that, the beginning of another ice wedge. It's most likely that Adams did, indeed, find clear ice that tasted terrible. 

Fig. 2. Mamontovy Khayata. Source.

On to the polygons. After examining the bluff, Adams walked inland to collect plant samples. He also poked at the tundra to see if the thickness changed. He saw a great amount of drift wood both on the shore and on the hills. The wood on the hills his Evenki hosts called Adam's wood. The wood on the beach, which came down the Lena every spring, they called Noah's wood. First Adams' comments on the Lena floods: 
J'ai vu dans les grandes fontes de glaces des grosses mottes de terre se détacher des collines, se mêler à l'eau et, former des torrens épais et argilleux qui roulent lentement vers la mer. 
All three English translations agree on the substance of this sentence. 
I have seen, in great thaws, large pieces of earth detach themselves from the hillocks, mix with the water, and form thick and muddy torrents, which roll slowly towards the sea. 
The next sentence is the one that I think describes patterned ground. 
Cette terre forme des figures de coins qui s'enfoncent entre les glaçons. 
The first published English translation (1807) reads: 
This earth forms in different places lumps, which sink in among the ice. 
The second English translation (1820) reads: 
This earth forms wedges which fill up the spaces between the blocks of ice. 
Finally, my crude translation: 
This earth forms figures, which settle among the ice. 
Mine, more or less, agrees with the first, but I've discovered errors in the first. The very reason I've made my own translation is to figure out which one is right when I discover variations. I've also retranslated two German translations because I'm that anal.

In context, the earth (terre) he mentions must be the same muddy earth that he saw during the spring thaw. That would be the same frozen mud that makes up the majority of permafrost. This ice (glaçons) should be the same as the ice (glace) he saw on the bluff face. Knowing what we know about permafrost, it makes much more sense for the earth to be surrounded by ice and not for the ice to be surrounded by earth. The Germans agree with me, though they also call the earth wedge-shaped (diese Erde bildet sodann keilförmige Figuren, welche sich zwischen den Eisschollen festsetzen). If anyone is fluent in French I'd like your opinion on this passage.

Ultimately, it's not important whether or not he got all of the details right. The important thing is that, at that early date, he mentioned the figures on the surface of the ground and correctly identified the underlying structure as being made up of separate parts of ice wedges and regular frozen mud permafrost. At a time when many scientists didn't even recognize the reality of permafrost, that was quite an accomplishment.

3 comments:

  1. I wonder if Agassiz was aware of this.

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  2. I'm not sure if he ever commented on permafrost. I know that after Agassiz one of the common terms for certain kinds of permafrost was "fossil ice," by which they meant those types of permafrost were buried glaciers. This is possibly the origin of the trope of mammoths being found in glaciers, which has never happened.

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