Description

2 COLOSSAL MAPS:

 

# 1.

Maurice J. GROLIER and William C. OVERSTREET / U.S. GEOLOGICAL SURVEY / NORTH YEMEN CENTRAL PLANNING ORGANIZATION.

 

Geographic Map of the Yemen Arab Republic (Şan‘ā‘).

 

Reston, Virginia: U.S. Geological Survey, 1978.

 

Colour print, housed within original USGS envelop with printed labelling (Very Good, clean, crisp and bright), 132 x 92 cm (52 x 36 inches).

 

[with:] 

 

# 2.

Maurice J. GROLIER and William C. OVERSTREET / U.S. GEOLOGICAL SURVEY / NORTH YEMEN CENTRAL PLANNING ORGANIZATION.

 

Geologic Map of the Yemen Arab Republic (Şan‘ā‘).

 

Reston, Virginia: U.S. Geological Survey, 1978.

 

Colour print, housed within original USGS envelop with printed labelling (Very Good, clean, crisp and bright), 132 x 106 cm (52 x 41.5 inches).

 

The Yemen Arab Republic, popularly known as North Yemen (centred on its capital Sana’a), was an Arab nationalist state that occupied the north-western part of Yemen, which existed from 1967 to 1990, until the two parts of Yemen were unified.  Due to its very rugged topography and political instability, until the 1970s North Yemen had never been geological surveyed, at least not in a scientific or comprehensive fashion.  This was despite the fact that its territory was known to be rich in oil and natural gas, as well as coal, gold, lead, nickel, copper, rock salt and marble.

As revealed upon the present maps, the geology of North Yemen is extremely complex.  The country rises from the Red Sea coastal plain (the tihama) to a high plateau that reaches its apex at the Jabal An-Nabī Shuʿayb at 3,666 metres (12,028 ft), a massif created by the violent convergence of the Arabian and African tectonic plates.  Much of the country was extremely difficult to access, in part due to the fact that many areas were often politically unstable and creating a scientifically accurate geological map of the terrain was considered to an immensely difficult undertaking.  While some good data and mapping of certain areas had been produced in the 1960s, this work was fragmentary, and it was clear that North Yemen simply could not be comprehensively geologically surveyed by traditional means.

By around 1970, it was clear that the development of the promising petroleum industry in North Yemen was being held back by the lack of a comprehensive geological map of the country, and the national government, based in Sana’a, was prepared to take action, capitalizing upon a period relative political and economic stability.

While the country was home to some fine geologists, the advanced technical resources required to make such a map were not present in North Yemen.  Consequently, the country’s Central Planning Authority and its Ministries of Economy & Agriculture and Minerals & Petroleum approached the U.S. Geological Survey (USGS) to create a comprehensive national geological map.  The Sana’a government was then an American ally and the USGS had estimable experience making geological maps of other Middle Eastern-North African countries, such as Iran, Libya and Saudi Arabia.

The USGS, recognizing that it was impossible to conduct a systematic geological survey of North Yemen on the ground, decided to engage NASA to employ Land Satellite (Landsat) technology to identify the country’s geological zones.  Once Landsat images were taken, they would be correlated to existing field data, while new field operations would be undertaken to double-check the Landsat findings.

In 1972, the USCS charged two of their finest geologists, Maurice J. Grolier and William C. Overstreet, to lead the project to create the first proper geological map of North Yemen.  To their specifications, from November 1972 to February 1973, NASA programmed their satellite to take several Landsat-1 images of North Yemen and adjacent parts of Saudi Arabia and the South Yemen (a key to these images is located in the inset found on both of the present maps).

Of the nine finished Landsat images, Grolier and Overstreet recalled in a December 1976 report:

“The intent in compiling these geologic maps [images] was to bring together, at a convenient working scale, previously known and recently acquired geologic data. It is hoped that this set of maps can be used as a tool in hydrologic investigations, minerals exploration, in regional planning, economic and industrial development, highway engineering, and, also, as an aid in mapping the regional geology of the YAR [Yemen Arab Republic] at a larger scale.” (Grolier and Overstreet, Preliminary Geologic Map of North Yemen… [U.S. Geological Survey Report] (December 1976), p. 2).

After having carefully analyzed the Landsat images, Grolier and Overstreet made a field trip to North Yemen in June-July 1975 in order to verify the information revealed by the images, and “to visit several mineral prospects, and to collect samples of rocks, ores, and slags”.  The samples were subsequently analyzed at the USGS laboratory in Denver.  In February, Grolier made a follow up trip to North Yemen.

After a further two years of analysis and proof-checking, Grolier and Overstreet integrated and distilled their raw Landsat images into the present Geographic Map of the Yemen Arab Republic (Şan‘ā‘) (Map # 1), which was published by the USGS in Reston, Virginia, in 1978.

To a scale of 1:500,000, the map presents a panoptic view of North Yemen, showcasing its extraordinary topographical diversity, with its great mountain ranges, wadis, oases and craggy shorelines, underlaid by a rich and complex diversity of geological zones.  Superimposed upon the photography is the labelling of key roads (in both Arabic and English) and North Yemen’s international boundaries (as dashed lines).

The Geographic Map was then used to create the present Geologic Map of the Yemen Arab Republic (Şan‘ā‘) (Map # 2), which followed the exact same perspective and scale.  Here, overlaid upon the Landsat photography is a pageant of colours representing the country’s various geological zones, along with the numerous fault lines and other features of this tectonically active land.  The legend in the righthand includes the ‘Correlation of Map Units’ identifing the various geological zones of Quaternary, Tertiary, Tertiary & Cretaceous, Jurassic, Ordovician and Precambrian, with each divided in sub-classifications.  Below the title is the ‘Description of the Map Units’ which describes the various geological sub-classifications, as well as identifying the symbols used to mark faults, folds, strikes, volcanic formations and mineral deposits of various kinds, as well as the locations of ‘abandoned exploratory oil wells’.  Importantly, this is the very first time that all of this information appears together on single map.

Immediately upon its publication, the Geologic Map of the Yemen Arab Republic (Şan‘ā‘) was hailed as tour de force, imbued with immense practical value to the North Yemen government and, of course, the oil and mining companies.  It was reissued, with updates, in 1983.

However, while Grolier and Overstreet’s mapping represented the first proper general geological mapping of North Yemen, there was room for their work to be continued, as further field exploration and more intensive satellite imagery could lead to further refinement of the cartography.

The North Yemen authorities therefore engaged the Bundesanstalt für Geowissenschaften und Rohstoffe, West Germany’s Federal Institute of Geosciences and Natural Resources, in Hannover, to continue the project.  Beginning in 1979, a team led by the geologist Wolfgang Kruck produced separate sheets of their Geological Map of the Yemen Arab Republic, done to scale of 1:250,000, which was only completed, upon al the issue of all 8 sheets, in 1991.  As North and South Yemen were united to form a single nation, the ‘Republic of Yemen’, in 1990, this mapping was subsequently integrated with the geological mapping of South Yemen to form a complete picture.

Examples of both the present Geographic and Geological maps of North Yemen are found in several institutions worldwide, many of which had subscriptions to USGS publications.  However, the maps, which were issue separately from one another, only very rare appear on the market, and it is indeed very unusual to find both maps together.

References: Re: Geographic Map: OCLC: 742956851 / 367801530; Re: Geologic Map: OCLC: 4644932 / 961313724; Cf. Maurice J. GROLIER and William C. OVERSTREET, Preliminary Geologic Map of North Yemen… [U.S. Geological Survey Report] (December 1976).