DEVILS TOWER
NATIONAL MONUMENT
Wyoming
UNITED STATES DEPARTMENT OF THE INTERIOR, J. A. Krug, Secretary
NATIONAL PARK SERVICE, Newton B. Drury, Director
An 865-foot tower of rock, serving as evidence ofvolcanic activity that occurred many millions of years ago
Devils Tower National Monument has thedistinction of being the first national monumentto be created. It was established by proclamationof President Theodore Roosevelt in the year1906 under authority of the so-called AntiquitiesAct.
The great natural feature, Devils Tower(known to the Sioux Indian as MATEO TEPEE,meaning Grizzly Bears’ Lodge), is like a hugefluted monumental shaft set upon a mound,alongside the Belle Fourche River and amidstrolling grasslands and pine forests.
The Tower rises to a height of 1,280 feet fromthe river bed and some 865 feet from its apparentbase on the hilltop. The diameter at itsbase is approximately 1,000 feet, and at the topaverages 275 feet. The top surface embracesabout an acre and a half, upon which mosses,ferns, grasses, shrubs, and sagebrush grow.Mice, pack rats, and chipmunks have been seenthere, and the falcon and hawk make it theirhome. As viewed from various angles, the Towerhas many shapes.
The fresh rock is of a dark grey color which,after weathering, bleaches to a light grey withtinges of buff. Lichens of various colors andshades grow on its face, reflecting tones oflight, so that in color its appearance may changeseveral times during the day, depending on conditionsof atmosphere and light. On occasion, ared sunset may give it a reddish glow, fading todull purple.
A Geologic Mystery
As to the mode of origin of the Devils Towergeologists are by no means in agreement. Thatthe rock of the Tower was at one time moltenand was forced upward from deep within theearth is no question, and that it cooled beneaththe surface is probable. But whether the greatshaft as it now stands is in reality hardened lavain the neck of an old volcano the enclosing wallsof which have been removed by erosion, orwhether it is part of a great sheet or sill ofmolten rock which was injected between rocklayers, cannot be positively stated.
On the basis of either explanation hundredsof feet of rock have obviously been removed byerosion from around the Tower and carried byrivers toward the sea.
The columns present an interesting problem.They appear to have been produced in therapidly cooling volcanic rock by regularly arrangedcracks which were due to contraction ofthe cooling mass. The fact that they are not welldeveloped in the base of the Tower may be dueto the slower cooling of the more deeply buriedpart. The flare of the columns is a subject tooinvolved for this brief account.
As to the age of the Tower it is believed to2have been formed early in the Age of Mammals,perhaps 50 million years ago, but to have beenuncovered by erosion only in the last one or twomillion years.
Plant and Animal Life
About a half mile from the entrance to DevilsTower National Monument the visitor findshimself driving through a thriving prairie dog“town.” These animals were as typical of theoriginal West as the buffalo. Their presence intowns covering several square miles was incompatiblewith agriculture, and the elimination ofthe species has progresse