Key to Grain Sizes and Types s = sand si = silt m = mud vf = very fine f = fine md = medium p = pebble g = gravel tuff. = tuffaceous Descriptive Abbreviations: d. silt lam. = discontinuous silt laminations in massive mud filled crack? = vertical planar features interpreted as mud filled cracks Key to Color Codes: 7.5YR5/4 = brown 7.5YR6/3 = light brown 7.5YR6/4 = light brown 10YR4/3 = brown 10YR5/4 = yellowish brown 10YR6/2 = light brownish grey 10YR6/3 = pale brown 10YR6/4 = light yellowish brown 10YR7/2 = light grey 10YR7/3 = very pale brown 2.5Y6/2 = light brownish grey 2.5Y6/3 = light yellowish brown 2.5Y7/2 = light grey 2.5Y7/3 = light yellow 5Y6/3 = pale olive 5Y7/2 = light grey 5Y7/3 = pale yellow 5GY5/1 = greenish grey