W-10 Arch Creek section. NW¼ SE¼ sec 14 T51N, R.66 W, just off rd to Moorcroft to W about ¼ mile before it turns W over ridge. Part-A Begins within Fell River at top of small butte ¼ mi N of where Moorcroft rd swings W up ridge. Measuring down 10.0 Sandstone, tabular cross-laminated to thin bedded. chiefly beds 0.4 to 1.0 buff weath. X-12m. with ripple-marked bedding surfaces, much "worm"trucking. Few thin beds & shaly laminated SS partings. Fine-grained. 7.3 Interbedded (and interlaminated) siltstone and fine-gr, ss with partings silty shale. chiefly lean siltstn, becoming gray & equillceous toward base weathous yellowish gray with some brown Fe stained layers Beds 0.1± , worm tracked places. 11.3 Shale, gray to dk gray with laminze and thin beds of 59