From: Terra Nova, Vol. 20, Issue 2 (April 2008) Blackwell Publishing Ltd.

Fig. 1 3-D view of Lake Cheko superimposed on an aerial photograph collected in 1999.

The peculiar nature of the "soft" target, a wet, swampy forested ground underlain by a >20 m thick permafrost layer has favoured an efficient energy transfer at a great depth and have attenuated the effects in the surroundings thus allowing the survival of trees at a short distance from the impact. Dewatering and degassing of sediments and permafrost due to the heat released by the impact followed by collapse of the walls of the crater, may well result in a crater morphology somewhat different from that predicted by standard models. The chaotic deposits detected below the thin upper layer of lacustrine sediments might represent material that collapsed and was reworked from the sides of the crater immediately following the impact. This would explain the absence of an elevated rim.

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