Recent Algal Stromatolites from the Canary Islands

Algal stromatolites (oncolites) occur on the insular shelves of the Canary Islands in the eastern Atlantic. Specimens from an unnamed bank in these islands are made up predominantly of the encrusting nullipore, Goniolithon accretum; vary in size between 0.5 and 10.0 cm.; are composed of calcite in association with magnesium and appreciable aragonite; and show distinct physicochemical and biogenic corrosion. An age of the interior of one oncolite was estimated by$C^{14}$to be 1,500±100 years B.P. On the bottom the oncolites occur in varying concentrations or in definite bands, ripple troughs, which are oriented northeast-southwest.