CAMBRIAN PERIOD.
Island of Islay.—Good evidence of ice-action has been observed by Mr. James Thomson, F.G.S.,[154] in strata which he believes to be of Cambrian age. At Port Askaig, Island of Islay, below a precipitous cliff of quartzite 70 feet in height, there is a mass of arenaceous talcose schist containing fragments of granite, some angular, but most of them rounded, and of all sizes, from mere particles to large boulders. As there is no granite in the island from which these boulders could have been derived, he justly infers that they must have been transported by the agency of ice. The probability of his conclusion is strengthened by the almost total absence of stratification in the deposit in question.
North-west of Scotland.—Mr. J. Geikie tells me that much of the Cambrian conglomerate in the north-west of Scotland strongly reminds him of the coarse shingle beds (Alpine diluvium) which so often crowd the old glacial valleys of Switzerland and Northern Italy. In many places the stones of the Cambrian conglomerate have a subangular, blunted shape, like those of the re-arranged moraine débris of Alpine countries.