| Text Description: |
Scoriaceous lapilli from lowermost of multiple beds each 5-20 cm thick. Vesicles and phenocrysts each range from nearly zero to 20% among lapilli; average is 73.9% pale yellow-brown glass 9.5% plagioclase 1.0% pyroxene 15.0% macrovesicles. Banding is defined in some lapilli by variable phenocryst size and content; one greywacke inclusion observed. | (Riehle) Creek bank w/ some mantle-bed dip-slope aspect. [Diagram] 1.2m: lower bed 40cm airfall yell lap to 5-6cm w/ 30% gy lith; overlain by several beds yell m-c ash & fine lap, gy lith <30% | SAMP E: Andesite. 60cm m ash to lap 2cm, blocky gy dac: 5cm f gy ash at top, 61% SiO2 glass | SAMP D: Low Si-dacite, 12cm m ash to 1cm lap, yell w/ 30% gy lith, 67.5% SiO2 glass | SAMP C: 20cm m ash to 1cm lap, gy, 2cm f gy ash at top | SAMP B: 4-5m, no evidence of soil development, locally in till, 51.5% SiO2 | SAMP A: 5-20cm beds f ash, m-c ash, lap to 1-2cm; darken down. Pale, drab gy-gn aspect, highly bimodal size (silt- f sand, pebs-small bldrs), overall massive but local bldr concentrations, pebs include volcs, granite, faceting/poloishing/striations well developed on 20% of clasts. |