and igneous boulders up to a foot in diameter with a calcareous cement as shown by its effervescence in acid, at least in the upper part. It was in all perhaps 100 feet in thickness. The upper part reminded me of the “mesa caps” in places north of Boulder where cemented by a calcareous matrix. Passed northward into Wyoming, thence westward passing around the head of Sand Creek and tributaries except one which we crossed, thence southward to Box Elder P.O. over the Cheyenne road and on to camp. Found nothing suggesting the limestone containing Carboniferous fossils mentioned by Darton et al. unless at northwest corner of the quadrangular course of the day’s travel. Saw about 75 piñon jays flying nearly north. Had a very hard day. It hailed about 10 a.m., immense hailstones falling, with very little rain, so that we kept moderately dry, lying under a low cedar which broke the fall of the hailstones. At 2 p.m. it began to hail and rain furiously and kept it up until we reached camp at 3:15, soaked through and chilled, the ground
