The Disturbance of Arctic Lake Sediments by “Bottom Ice”:
borne observations of “mud-centre’ ’ tundra lakes in Manitoba. The mud flats (ap-parently not remanent “rotten ice”) which occupied the middle of these arctic lakes in July had occasional rocks, sticks, bones, and caribou antlers on the surface. No firm conclusion was reached as to their origin. The...
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1028.3429 http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/download/3295/3271/ |
| Summary: | borne observations of “mud-centre’ ’ tundra lakes in Manitoba. The mud flats (ap-parently not remanent “rotten ice”) which occupied the middle of these arctic lakes in July had occasional rocks, sticks, bones, and caribou antlers on the surface. No firm conclusion was reached as to their origin. The present observations are believed to have some bearing on the problem. The author spent most of June and July 1966 camped beside a small unnamed lake (about IOO metres long and 3 metres deep) approximately 15 kilometres north of Pelly Lake, close to the Arctic Circle (66’05’N., 101~04’W.). The lake was largely frozen on arrival in the area on I 5 June and the surface ice had melted by I July. A week of almost continuous sunshine followed, with mean daily air temperatures of 16Oc. and mean daily water temperatures in very shallow ponds (25 cm. deep) of up to 14OC. By contrast, the water of the lake next to the campsite remained close to freezing point, due no doubt to the presence of ice on the bottom of the lake, which could be perceived from the bank. After the surface of the lake had been ice free for about a week, there occurred a disturbance of the lake waters and I was able to observe “bottom ice ” floating to the surface in massive blocks several metres in length and at least one metre (estimated) in thickness. This ice was quite dark, being impregnated with sand and mud, and seemed to contain a large portion of the lake sediments. The floating ice melted in a few days, and then the water temperature rose rapidly. I suggest that this may be the origin of the phenomenon described by Bryson and Ragotzkie ’ as a “mud-centre ” lake. I had been exploring the area for fossil organic materials- particularly peat- for a palynological study of former climatic changes. I was therefore very concerned to “Mud-center’ ’ tundra lakes. Limnology end |
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