Our team's geomorphologist Professor Joaquin Rodriguez Vidal came up with an amazing discovery the other day. Examining the excavation at Vanguard he saw this broken stalactite which had been embedded within the sediment until it was excavated by our team. With other evidence of significant deformation of cave materials elsewhere in the site, he concluded that this represented a large earthquake that shook the Rock some 40 kyr. The stal broke but the sediment it was in held it in position. Joaquin reckons the quake was local, with its epicentre on the Rock itself. The result was the sudden elevation of the Rock by 2 cm!
Amazing just one picture captures the idea that 40,000 years ago the rock rose or its foundations dropped. hmmm so what stopped the rock from just falling back into its original position? I say this because there appears to be little lateral movement that can be seen and I guess it would take something pretty substantial to hold the weight. (Sorry if Im willing something obvious - I'm an engineer not a geologist)
ReplyDeleteThis is just one example and there is evidence of lateral movement also in other areas of the cave. The whole of the Rock is uplifted, and it didn't fall back down again, clearly.
DeleteCool!
ReplyDeleteIf I remember there is also evidence of an earthquake sometime during the early sequence at Kent's Cavern.
ReplyDelete