(MP-70) Angostura dam section - Measured in exposures in SW-facing ledges under high point just SE Angostura dam in SE cor NW¼, sec.20 T8S, R6E, Angostura Reservoir quad., SD Begins just above water level (about 8±) at distinctive ledge very fine grained SS. Measured up. (1) 0.4 - ? Claystone, silty, dk grey, some greenish cect, with circular, flat patches white silt(?). (2) 0.8 ± Sandstone, very fine-grained, massive white-weathering, sparkly, with numerous dark + red grains. (3) 41. 0 dk purple+ Claystone, dzrk grey to greenish grey, silty. Basal 0.3 ± is sandy; a bed of finely sandy siltst. + loc u-f ss 0.4 thick lies about 110 above base. (4) to white 0.7 → 2.0 Siltstone, light grey, prcy lzm with silty to sandy clsty, forms massive blocky bed, loc goes to v-f ss Has Fe specks. w 45.9-50.0 (5) Sandstone, massive, cross lam to cross bedded. (5) Basal 13-15' conglomeratic, in stringers and in massive lvrcg bed 33