. The Quarterly journal of the Geological Society of London. 20 6. x6 9S*-2Prf. II^ Photo Bemrose Colic, Derby. MICROPHOTOGRAPHS OF ROCKS FROM THE FORFARSHIRE COAST. Yol. 69.] VOLCANIC EOCKS OF THE FOBFAESniEE COAST. 483 torrent-action. How did the Author explain the occurrence of thesedimentary material in the interstices of the lava ? Was it washedin by the water of a lake, or by rain-water, or was it the result of«eolian action? The suggestion that .cavities were formed by steamin sedimentary rocks below a lava-flow was very valuable. Dr. J. V. Elsden remarked on the petrographical int
. The Quarterly journal of the Geological Society of London. 20 6. x6 9S*-2Prf. II^ Photo Bemrose Colic, Derby. MICROPHOTOGRAPHS OF ROCKS FROM THE FORFARSHIRE COAST. Yol. 69.] VOLCANIC EOCKS OF THE FOBFAESniEE COAST. 483 torrent-action. How did the Author explain the occurrence of thesedimentary material in the interstices of the lava ? Was it washedin by the water of a lake, or by rain-water, or was it the result of«eolian action? The suggestion that .cavities were formed by steamin sedimentary rocks below a lava-flow was very valuable. Dr. J. V. Elsden remarked on the petrographical interest of thepaper. Some of the rock-types appeared to be rich in magnesia,and the augites might be expected to show the basal striationcharacteristic of such rocks in other areas. He asked whetherthese various rock-types occurred in separate lava-flows,- or in•different parts of the same flow. The character of the phenocrystssuggested an origin from a differentiated magma-basin. It wouldbe interesting to know what kind of rocks marked the dyke-pbase•of these eruptions.
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectgeology, bookyear1845
