Triassic limestone conglomerates. On Sunday after seeing the Cambrian lime- stones I am now certain that the Triassic conglomerates are derived from those limestones that once extended across the Blue Ridge and Catoctin Mountains. The milky white and banded limestones are still present in great abundance west of Hagerstown. The fact that the Triassic conglomerates contain no chalk is due to the different climate that prevailed in Triassic time when compared with the humid one of today. The former was drier and produced no residual clays. As there are no Cambrian quartzites in the Triassic conglomerates we must then assume that those did not extend across the Blue Ridge or at least not across Catoctin Mts. Fix of my paleogeographic maps accordingly, also those of Triassic time for the wider area of continental deposition.