A pelagic or hemipelagic sediment (an arl), typically found interbedded with purer oozes in beds up to 1.5 m thick, with a composition intermediate between a non-biogenic sediment and a calcareous or siliceous ooze. It is 30% clay and 70% microfossils, at least 15% of its volume being siliceous microfossils. Comparesarl; smarl.
Geography
Clay, usually alluvial, rich in soft calcium carbonate. See Cerdà (1999) Soil Sci. Soc. Am. J. 63 on comparative erosion rates in marl, clay, limestone, and sandstone.