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Unformatted text preview: LECTURE 12 - GLACIOLACUSTRINE AND GLACIOMARINE SEDIMENTS GLACIOLACUSTRINE SEDIMENTS IN N.A. (SOFT CLAYS) distribution and age most 18,000 to 6,000 ybp generally younger northward some still being deposited sedimentology associated with proglacial lakes processes involve overflow, interflow, underflow proximal facies underflow dominated sediment associations waterlaid tills flow tills subaqueous fan deposits deltaic deposits distal facies combination of dispersal mechanisms sediment associations parallel multilaminated beds (rythmites) ball and pillow structures drop stones and disturbed laminae DELTAS upper delta foresets underflow dominated system sed. transport by quasi-continuous currents grain flow and intermittent avalanches in places slump gen. surge currents may domin. sediments steeply dipping rhythm. bedded sand/gravel beds fining upwards sequences due to high disch. events distrib. channel shifts up to 1 m thick large clasts oriented paral. to dip some imbrication cross bedded sands rare/ clay absent...
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- Spring '08