USGS visual identity mark and link to main Web site

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

This page is <>
Maintained by Eastern Publications Group Web Team
Last modified 28-Feb-2001