BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VOL. 55, PP. 783-788 JUNE 1944 MILITARY GEOLOGY: A pplications o f G eo lo g y to T e r r a in I ntelligence BY CHARLES E. ERDMANN CONTENTS Page Introduction................................................. 783 Place of geology in terrain intelligence 785 Technique of geologic terrain analysis. 786 References cited........................................... 788 INTRODUCTION About a year ago an abstract of a German article on military geology appeared in the The Military Review (Command and Staff School, 1943) and called attention to the employment of a geological section of nine men by each German army. Every adversary of these forces has yielded reluctant admiration to their most skillful use of ground, and there is reason to believe that applications of geologic science have made substantial contributions to their successful exploitation of terrain. By their own admission, we know that they have used geology in administrative and opera­ tional problems, and it is logical to conclude that they have also found geology adapted to certain phases of military intelligence. This formal usage of military geology is presently in great contrast to its somewhat indifferent use, or even lack of use, by the Army of the United States. Indeed, in our Army less progress in military geology has been made in World War II than in World War I, when authority existed for the assignment of five geologists to each Army, or one for each Corps—despite the fact that the varied geography of the far-flung theaters of the current war and the character of combat within them require much more intense application of every possible method of terrain evaluation than did the fighting in northern France some twenty-odd years ago. This does not mean that our effort in World War II wholly lacks geologic technique. On the contrary, War Department intelligence (Intelli­ gence Division, Corps of Engineers) is being prepared by the Military Geology Unit of the United States Geological Survey, and ground-water geologists of the Survey are functioning with engineer water-supply battalions; but there has been no general recognition of a place for a geologist with combat forces. Nevertheless, some geo­ logic techniques for field forces are being carried out by men of other sciences, such as studies on soil trafficability by certain meteorological sections of the Army Air Force (Link, 1943). Obviously, this situation is the product of a definite need; and the question whether it is being met in the most efficient manner can be argued from the standpoint of the military principle of economy of force. Whatever the nature of the precipitation, once on the ground it becomes a geologic agent operating upon geologic materials, and only the geologist has been trained to analyze the process and 783 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/55/6/783/3416345/BUL55_6-0783.pdf by guest on 27 September 2021 784 C. E. ERDMANN— MILITARY GEOLOGY its results in detail. Hence he believes that, given the weather prediction, he is far more able to foresee its effect upon terrain and mobility and operations as a whole than the meteorologist. Because of differences in kind and attitude of bedrock, character and thickness of mantle rock or surficial soil, topography and vegetation, and rate of rainfall, rates of absorption and runoff may change rapidly from place to place. Geologic methods of terrain analysis may reveal unsuspected wet-weather routes in advance of cross-country movement that might otherwise be found only by trial and error or through the favor of friendly inhabitants after the ground is reached; they can certainly indicate in advance of a weather forecast the most favorable of alternative dry-weather routes, or the reaction to traffic of various kinds of ground under different conditions of rainfall, on the chance that unpredicted inclement weather might overtake a field operation in progress. Reasons for the nonemployment of geology by our Army are probably both ad­ ministrative and technical. Only the technical reasons need concern us here, for they must be overcome before any administrative progress can be made. The gen­ eral attitude of the Army toward the military application of any science has been expressed as follows: The adaptation of new scientific developments to war is gradually making the task of G-2 more complex; at the same time, however, it affords him an additional means for the collection of informa­ tion. (FM 30-5, par. 14d) This quotation is especially pertinent with respect to geology because that science does afford an additional means of information that no other can supply, and, as will be shown, if properly applied it should simplify rather than complicate the task of G-2. Why then, one may ask, is it not put to greater use? Perhaps there is some ques­ tion as to its proper place in Army organization. Another reason may lie in the very nature of geology, for it is admittedly a “circular subject”; that is, there appears to be no obvious or convenient place where a layman can grasp it. Thus, in physical geology consideration of processes presupposes some knowledge of the materials upon which they operate, and discussion of materials leads back again to processes. All the more reason, then, why the various aspects of geology should be handled by those who have been trained in its techniques. On the other hand, the military method of terrain evaluation on the “basis of observation and denial of observation” (FM 5-15, par. 9a(l)) is wholly artificial and incompetent to develop the fundamental char­ acteristics of terrain. Admittedly, it is very practicable and suffices to evaluate the conventional military factors of terrain appreciation, observation, fields of fire, cover and concealment, obstacles, and communications; but it leads away from rather than to the essential elements, which constitute the substance or nature of the terrain it­ self, and these elements are what actually control whatever view the observer can obtain. Because of this exclusion the soldier is inclined to ask: How can the geologist tell so much about terrain from geology? Insofar as the writer’s studies have been carried, only one obscure paragraph of Army doctrine (FM 21-26, par. 40A) gives recognition to this question, and it comes under the heading of “Relief” rather than “Terrain” : Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/55/6/783/3416345/BUL55_6-0783.pdf by guest on 27 September 2021 INTRODUCTION 785 As the exact nature of the terrain has a marked influence on military operations, it is important that the military commander of every unit familiarize himself with the ‘lay of the land’ in which he is operating. This familiarity cannot always be obtained by actual reconnaissance beforehand but often must be gained solely by study of topographic maps. The map, then, must convey to the map reader a definite impression of the ground forms. The ability to comprehend, relief from the map re­ quires an understanding of the way in which tke various ground forms have been produced by nature. (Italics are present author’s.) This realization of the intimate association of geologic agents with land forms, and the ability to interpret their origin and evolution from topographic and geologic maps or aerial photographs, is why the geologic method of terrain appreciation yields superior and often unsuspected technical information that may have practical tac­ tical value, without in any way restricting the scope of other military operations.. In fact, it supplements them, and its application assures that no basic factor of terrain will be overlooked. Hence the fundamental contribution of geology to military opera­ tions is superior information. The purpose of this article is to suggest the proper place of geology in Army organization, to indicate how well prepared the structure of this organization is to receive it, and to show how geologic data are assembled and converted into intelligence. PLACE OF GEOLOGY IN TERRAIN INTELLIGENCE The mutual relationship between geology and terrain, or, as the soldier sees it, the landscape, is axiomatic. There is an equally close connection between land warfare and terrain. Without some good earth the terrain factor would not exist,' as in naval warfare. Obviously, then, the common denominator of land warfare and geology is terrain. By substituting geology for terrain in the above equation, its place in our military doctrine is determined at once. Based upon source of information, military intelligence is classified into War De­ partment intelligence and combat intelligence. Presumably War Department in­ telligence is carried on in time of peace, and the results obtained are furnished to the field forces prior to operations, but its activities do not terminate with the recognition of a state of war. The Basic Field Manual on Combat Intelligence, FM 30-5, par. 3b, lists numerous topics within its scope, among them military geography and topography. Unquestionably, future revisions of the paragraph cited will include military geology, because the resolving power of geologic analysis, especially with respect to terrain, is much more definitive than that of the pseudo science of geogra­ phy. War Department intelligence is the very foundation of geologic terrain analysis. Without large highly specialized libraries rich in geologic and topographic maps of all lands, scientific and technical publications of all kinds and in all lan­ guages, and a competent analytical staff, the basic compilations could not be made. Combat intelligence is derived from the interpretation of military information in the field in the presence of the enemy, and its chief concern “is to reduce as far as possible uncertainties regarding the enemy and local conditions and thus assist the commander in making a decision and the troops in executing their assigned mis­ sions.” (FM 30-5, par.