U.S. Geological Survey
Geologic Investigations Series I 2720
2000
Online version 1.0

A Tapestry of Time and Terrain

By José F. Vigil, Richard J. Pike, and David G. Howell

thumbnail version of the map

INTRODUCTION

Through computer processing and enhancement, we have brought together two existing images of the lower 48 states of the United States (U.S.) into a single digital tapestry. Woven into the fabric of this new map are data from previous U.S. Geological Survey (USGS) maps that depict the topography and geology of the United States in separate formats. The resulting composite is the most detailed and accurate portrait of the U.S. land surface and the ages of its underlying rock formations yet displayed in the same image. The new map resembles traditional 3-D perspective drawings of landscapes with the addition of a fourth dimension, geologic time, which is shown in color. This union of topographic texture with the patterns defined by units of geologic time creates a visual synthesis that has escaped most prior attempts to combine shaded relief with a second characteristic shown by color, commonly height above sea level (already implicit in the shaded relief). In mutually enhancing the landscape and its underlying temporal structure, this digital tapestry outlines the geologic story of continental collision and break-up, mountain-building, river erosion and deposition, ice-cap glaciation, volcanism, and other events and processes that have shaped the region over the last 2.6 billion years.

The terrain

One of this map's two components is a digital shaded-relief image that shows the shape of the land surface by variations in brightness. The degree of light and dark artificially mimics the intensity of the Sun's light on different types of topography.

Geologic time

The second component of this tapestry, color, represents geologic time and is simplified from the geologic map of King and Beikman. Rocks contain information essential to an intelligent understanding of the Earth and its long natural history. Geologists determine the location, geographic extent, age, and physical and chemical characteristics of rocks and unconsolidated (loose) materials.

Download the Map Files
File Name	Description	File Size
i2720.pdf	PDF file of the tapestry map for plotting	36 MB

	If you would like a version of this map that has a white background, oceans, and lakes with black lettering (uses less ink), contact Mike Diggles.

i2720pamphlet.pdf	PDF file of the accompanying pamphlet	45 MB

Download a free copy of Adobe Reader

For questions regarding this report, contact David Howell or Dick Pike.

The full dataset for the topography layer for this map is available from the website for I map 2206

Read Phil King's autobiography, U.S. Geological Survey 0pen-File Report 00-443

This map and the accompanying pamphlet are also available from:

USGS Information Services, Box 25286,
Federal Center, Denver, CO 80225
telephone: 303-202-4210; e-mail: infoservices@usgs.gov

URL of this page: http://pubs.usgs.gov/imap/i2720/
Maintained by: Michael Diggles
Created: May 31, 2000
Last modified: July 9, 2007 (mfd)