Ten busy months had passed since the pioneering trio of explorers, wearing beards and Arab garb, had made its historic rendezvous at Jubail, on Saudi Arabia's east coast. Now "Krug" Henry and another geologist, J.W. "Soak" Hoover, who had joined the group in October, a month later, escaped to the relative cool of Dhour Choueir, Lebanon, to record their observations and impressions. The account, like others to follow, was written primarily to inform their employer in far-off San Francisco, Standard Oil Company of California, holder of an oil concession agreement with the Saudi Arab Government. Hoover and Henry composed it in the simple, straightforward prose demanded of all effective business and scientific communications. A careful reading by other geologists would have uncovered cautious hints of possible future oil finds. No one, however, could have foreseen in those days that the earliest geologic report would become basic source material for a 30-year exploration project utilized in turning the Arabian Peninsula, then a land whose interior features were almost completely unknown, into one of the best-mapped areas in the world.
Now the products of that long effort have been published: 1: 2,000,000-scale geographic maps of the Arabian Peninsula as a whole, in separate Arabic and English-language editions; an English-language geological map drawn to the same scale; 21 geographical and 21 geological, 1: 500,000-scale regional maps in both Arabic and English—a total of 45 individual sources of information about the vast subcontinent which runs southward from the borders of Jordan, Iraq and Kuwait to the tip of Aden and the Arabian Sea.
The mapping project called for the full, not to say unique, cooperation among governments, oil companies and private individuals. Even its conception was group-inspired. The idea came out of some discussions held back in 1951 by William E. Wrather, then director of the U.S. Geological Survey, the late George Wadsworth, who at that time was the American ambassador to Saudi Arabia, and James Terry Duce, a vice president of the Arabian American Oil Company, now retired. The Saudi Arabian Government and the U.S. Department of State agreed to be co-sponsors. Active participation in the project was divided between Aramco and the Geological Survey, with contributions by the Saudi Arabian Ministry of Petroleum and Mineral Resources.
For purposes of the undertaking the Kingdom of Saudi Arabia was marked off into 21 quadrangles, each three by four or more degrees square, the rough equivalent in area of the state of North Dakota. It was agreed that Aramco would be responsible for mapping 14½ of these quadrangles, located in the eastern half and the northern and northwestern parts of the country. Aramco geologists had already classified them as sedimentary rock areas, characterized by sandstone, shale and varieties of limestone, where oil is most likely to be found. The U.S.G.S. would map the remaining 6½ quadrangles, lying in the western third of Saudi Arabia and classified geologically as mainly crystalline ("hard rock") area.
Five years before the project formally got under way in 1954, sharp-eyed residents of Saudi Arabia's Eastern Province could see a tiny speck high in the sky cruising in a long straight line. The object of their interest was a converted B-17 which carried in her belly a six-inch focal length aerial camera with a metrogon lens. Intermittently from that time through early 1959 the plane was to crisscross in a well-defined pattern high over the gravelly plains of the northern Najd, the sandy wastes of the Rub' al-Khali, the 10,000 foot-high peaks of 'Asir Province deep in the southwestern corner of Saudi Arabia, and, under Saudi Arabian Government auspices, the Precambrian rock area of the Hijaz, in the western part of the Kingdom. When the plane's assignment was finished, 1,165,000 square miles had been covered and Saudi Arabia became one of the few countries anywhere to be completely photographed from the air.
The use of aerial photography as an aid in map-making has been described by one writer as the greatest advance in cartography since the invention of the compass. The basic idea is well over 100 years old. Beginning in 1849, a French army engineer named Aime Laussedat made a series of photographs over Paris with ingenious combinations of balloons, kites and tiny sails. Early cameras secured to captive balloons were used to obtain topographic information in the U.S. during the Civil War. As techniques for making measurements in mapping became more refined, a new name was coined for the science: photogrammetry. Special applications of the principles of optics to steadily-improving aerial cameras moved photogrammetry ahead, but the biggest breakthrough came, of course, with the appearance of the airplane.
The focal length of the aerial camera, and the flight altitude from sea level, taking into account the average elevation above sea level of the terrain photographed, determine the scale of a vertical photograph taken from the air. Because of the large area requiring coverage for the Arabian Peninsula mapping project, as well as for other purposes, it was decided to work with aerials made on the relatively small scale of 1: 60,000. This required the photography plane to fly at a constant 30,000 feet above the terrain level, or elevation, it was shooting—an elevation commonly traveled by today's jets. But the aircraft doing the photography was of a non-pressured variety, which meant that flight and photography crews had to be sustained by oxygen. At more than 5.6 miles up, the air even over the baking Rub' al-Khali gets cold, with temperatures down to around minus 30° F. The men flying in that B-17 had to see to it that they were dressed for the occasion!
The photography plane was required to fly perfectly level, in order to avoid distortion and scale divergence in the pictures, and at exactly 30,000 feet above the terrain, to give each photograph proper scale for meeting strict photogrammetric specifications. The pilot had to fly in a consistently straight line, and to know precisely where he was at all times. The latter demands called for aerial navigation of a very high order.
Electronic navigation, employing a system known as Shoran, was brought into service over the Rub' al-Khali sand region of Saudi Arabia where the topography did not lend itself readily to visual navigation. Radar signals were transmitted between the aircraft and usually three widely-separated receiving stations located at geographically fixed known points on the ground. Thus the exact position of the plane at the instant of exposure of each photograph was recorded by measuring the time it took for the signals to make a round trip between the plane and the fixed ground stations. Through calculations using these data, the precise geographic coordinate of the physical center point of each aerial photograph was obtained.
As the plane flew back and forth in parallel straight lines from one predetermined position to another, the aerial camera shutter, controlled by an automatic tripping device called an intervalometer, exposed film about every 55 seconds. The camera was set to take each successive picture with a minimum overlap of 60 per cent on top of the preceding photograph to enable the cartographers in the map-making process later to view these photographs stereoscopically.
At the end of each run the plane wheeled around and headed in the opposite direction. Every exposure photographed a piece of Saudi Arabia measuring about 70 square miles. Since the stereoscopic viewing equipment and photogrammetric solution by the slotted template assembly demanded, in addition to the substantial forward lap, a 30 per cent side lap on both edges (between flight lines) of every picture shot, it worked out that each pass the B-17 made in one direction was no farther than about six miles from the course just flown parallel to it going the other way. And there are a great many six-mile intervals, averaging about 11 flight lines for each degree of latitude, lying across a nation as large as Saudi Arabia. That is one reason why the aerial photography phase alone had to be measured in terms of years. Another had to do with local weather conditions. The aerial photography program was carried out on a strictly seasonal basis because exacting specifications demanded clear photographs which could be taken only with a minimum cloud cover and in an atmosphere that was essentially free of dust and haze.
As thousands of aerials came pouring in, Aramco and U.S. Government map-makers tackled the tedious but exacting job of translating them into 1:500,000 and 1:2,000,000-scale maps constructed on a Lambert conformal conic projection. With the aid of meter bar and mathematic tables, latitude and longitude graticules (intersections) were established on each new map projection copy. The differing scales of the individual photographs and the map bases proper had to be reconciled by use of the slotted template method, first utilizing a proportional radial line plotter. From the plotter, radiating slots—their direction determined by image points common to overlapping photographs—were punched into cardboard templates for use in the crucial slotted template assembly for establishing control points common in horizontal positioning to both the aerial photographs and the map projections.
The most basic information cartographers work with is, of course, the measurements that have been made of horizontal distances and directions and the differences in elevations of the terrain they are mapping. A system of these measurements is called cartographic control, and any ground station in a horizontal and/or vertical control system that can be identified on a photograph and used for correlating the data shown on that photograph is a control point.
Certain control points set out on the Saudi Arabian landscape were easily identified on a pair of aerial photos viewed through a stereoscope, which brings out these points in third dimension. However, locating control points was difficult and time-consuming in certain regions of the Rub' al-Khali, where the sand terrain shows itself to be remarkably featureless and uniform, even on a long series of aerials strung together. In these types of terrain where problems with identification were anticipated and it was economically justifiable, key control points—triangulation, astronomical and level-line bench marks—were outlined prior to aerial photography with large asphalt circles which later could be picked out and identified on the aerials. Even this seemingly small refinement, though not widely used, had to be bought by much hard work. It required Aramco to truck asphalt great distances to remote areas separated from its refinery source in Ras Tanura by extremely difficult driving conditions.
Major control points which tied the whole Arabian Pensinsula mapping project together horizontally were located largely by taking observations of stars, by establishing triangulation nets and by the Shoran method. But as cartographers began to fill in the empty spaces on their maps, they went to more detailed measurements, making use of many which had previously been made on the ground by geological field parties. It was at this juncture that the old field notebooks of "Krug" Henry, "Soak" Hoover and their numerous successors in the field were taken out of the Exploration Department vault and opened for ready—and welcome—reference.
If the results of their labors were invariably of a high standard, the means these pioneering geologists used to delineate the land were often elementary in the extreme. They measured distances in more remote areas by automobile speedometer and determined directions with a Brunton compass. Although the more accurate plane table method was used extensively in coastal areas, an aneroid barometer commonly determined elevations and dips elsewhere.
Exploration Department map-makers, many of whom were also experienced field geologists, were thus able to learn from the Henry-Hoover report on field work completed in June 1934 that "the Eocene sediments (formation) and those post-Eocene rocks immediately overlapping (it) ... resulted in the formation of a large structure involving an area of some 150 square kilometers."
The cartographers and geologists knew just how to make maximum use of a descriptive passage such as that taken from field geologists K.R. Parsons' and R.B. Carr's 1941 geological report on the En Nala-Wadi Faruq area, situated west of Hofuf:
"The floor of the wadi (Wadi Faruq) averages about 10 kilometers in width south of the Jebel El Haya region. It is made up of drifting sands, dikaka, gravels and patches of marl. It is undulating in character, elevations in it varying considerably. Elevations in general rise gradually southward from an average of 215-225 meters in the north to 275-285 meters at the junction with Jau Kukhan. Topographic relief averages 50 to 60 meters between the wadi floor and the plateau areas on either side."
A somewhat sardonic note on plant life in north central Najd, written after a 1948 trip through upper Saudi Arabia, was almost as informative—in a negative sort of way. The description bears the stamp of geologist Don Holm, who before his retirement was Aramco's unofficial authority on local natural history:
"As a natural result (of recent showers) the desert broke out in a green rash of vegetation. Some of the bare silt flats of last year became as green as a golf course fairway. Flowers, though usually rather small, were abundant and the fragrance often gave rise to the illusion of being in fairer fields."
When drafting the immensely detailed geologic maps such observations as the following, made by R.D. Gierhart and L.F. Ramirez on their 1949 investigation of Saudi Arabia's southwestern corner, were indispensable. Describing the general physiography of the region around the Wadi Dawasir-Najran area, the geologists wrote:
"One of the most characteristic features of the area is the pediment, either sandstone or basement, which occurs around the edges of the Wadi sandstone hills. This pediment ranges from one to twenty kilometers wide and is best seen north of Bani Sanamma where the actual contact cannot be seen but can be inferred by the presence of a quartz gravel train which is the remains of a basal conglomerate seen in place south of Umm Rugaybah {19° 38' 10.7" N., 43° 57' 22.4" E.)"
In a U.S.G.S. professional paper, which describes the geology depicted on the new 1:2,000,000-scale map of the Peninsula, Aramco's Exploration Department listed in alphabetical sequence the names of 77 geologists who over three decades were on field parties which collected such data. Among those mentioned in the normal order were Max Steineke and Dick Bramkamp. Between them they occupied the post of chief geologist for 22 consecutive years—from 1936 through 1958—and either carried out personally or directed most of the gathering of the information. Another name on the list, appearing in the "B's", is Thomas C. Barger, who began his career with the company in 1938 as a young geologist and is now president and chief executive officer of Aramco.
The contributions each of these men made to knowledge about the physical and geological side of Saudi Arabia were important in themselves. Many aided the map project further by jotting down whatever Arabic place names they ran across in their field explorations. Their diligence, and years of patient sifting by Aramco's Arabian Affairs Division personnel put countless hills, valleys, plains and especially villages and towns on the map for the first time.
It worked this way: an oil explorer on a field trip would see, for example, a jabal (hill) in the distance and ask his Arab guide and local inhabitants what it was called. Some geologists who were proficient in Arabic were able to write in their notebooks the name of the jabal in that language. Others not so well equipped linguistically would put it down in writing the way it sounded to them. By whatever method, the explorer recorded the name, with its precise location, on his field map and in his report. Back in Dhahran, a geographical analyst gathered a number of Bedouin "relators" familiar with the area around a map of the particular quadrangle concerned and by careful cross-questioning determined the exact Arabic name by which the feature is known locally. The final name chosen usually represented the consensus of from three to ten informants.
After determining the meaning of a dialect place name, researchers worked toward establishing its exact equivalent in the alphabet of classical Arabic. They then combed through company library sources to see whether the landmark in question had ever been mentioned in print, especially by geographers writing in classical Arabic, as an added check against their own findings.
Important geographic and geologic information on the peripheral areas of the Arabian Peninsula outside Saudi Arabia was contributed by cooperating oil companies, governments and private individuals. This cooperation made it possible to depict, on a mutually beneficial basis, geologic and geographic map detail for the entire peninsula.
Even though taken from an altitude of 30,000 feet, the aerial photographs used to help map Saudi Arabia itself were often sharp enough in contrast to show up black-colored Bedouin tents staked out on the terrain. On most aerials studied, features of significance were right out in the open where they could be clearly seen. The map-makers found them easy to interpret because, in arid Arabia, trees, bushes and what scientists call "residual soil mantle" seldom, except for sand cover, obscured the essential surface expression of the-land.
If the openness of the landscape simplified photographic interpretation, Saudi Arabia's current and active economic expansion, on the other hand, created a few problems for the map-makers. As one instance, the country has been undergoing a very ambitious road-building program. Cartographers indicated all the hard-surface and natural surface highways existing right up until their cut-off time, knowing very well that their highway information would become out of date even in the short interval between completion of the maps and their publication.
As they stand now, however, the maps are already being used for one of the main purposes for which they were intended: providing the Saudi Arabian Government with firm data for an orderly scientific and economic development of the Kingdom. Their accuracy and detail are such that they can be indispensable in the planning of roads, towns, agricultural programs and mineral exploration. As educational tools, 2,000 relief maps in Arabic, based on the 1:2,000,000-scale geographic edition, are to be presented by Aramco to schools throughout Saudi Arabia.
In addition to their obvious use as guides to further oil exploration and development programs the new maps have handed Aramco one minor, pleasant benefit as well. Several of the finished products carry graphic evidence of how correct were the predictions of its early oil explorers. In their geologic report of 30 years ago the team of Henry and Hoover said: "From a consideration of structural and stratigraphic conditions which prevail in the Dammam area .... the writers feel justified in recommending that a test well be drilled on the Dammam Dome."
On Geographic Map 1-208-B, which takes in the region they covered in their earliest reconnaissances, is a dot right on top of Dammam Dome. It is the cartographic symbol for an oil well—Dammam No. 7—the first in Saudi Arabia to produce oil in commercial quantities—and still going strong.
Brainerd S. Bates, a writer with Aramco Public Relations in Dhahran, Saudi Arabia, spent three years in Majorca, Spain, as a free lance writer before joining Aramco in 1957. A graduate of Brown University in Providence, R.I., he is a former editor of Aramco World and contributes regularly to numerous oil publications.
