Namibia, the country in southwestern Africa, is known to geologists and geomorphologists for its unique geologic, tectonic, mineralogic and geomorphologic features. For more than 100 years, geoscientists have studied this country. As early as 1903, the Geological Survey of Namibia was founded, at first as a mining commission associated with the Preußische Geologische Landesanstalt. Namibia became one of the African countries most closely studied by geologists. Research results from southwestern Africa have influenced geologic and tectonic science in many ways (e.g., continental drift theory, snowball concept). Past geologic researchers in Namibia include names like ERICH KAISEr, who in 1926 wrote two volumes on the diamond desert of Southwest Africa, REINHARD MAACK (1969), who supported A. Wegener’s theory with observations from Namibia and Brazil, HANS CLOOS, who in the 1930s explained the formation of igneous rocks, and HENNO MARTIN, who with his students greatly influenced geologic research in Namibia during the last 50 years (Communications 2000). The fascination of Namibia’s geology is such that it has been described by scientists not only in scientific papers for experts, but also in books appealing to a wide readership.
It is surprising that Namibia’s geology has not yet been summarized in a single geologic publication. Unfortunately, the book by SCHNEIDER and co-authors will not fill this gap. However, those interested in the geology of Namibia will find a brief, very informative introduction that satisfies from a scientific perspective. The author has been working at the Geological Survey of Namibia for the past 20 years. Since 1996, she has been the director of this agency. For Roadside Geology, she found 20 co-authors who are very familiar with Namibia’s geology.
Roadside Geology is divided into three parts. (1) Overview: After the introduction, this chapter discusses the geological evolution of southern Africa and Namibia from the Archaean (starting 2.6 billion years) to the Cenozoic. This compressed description of the tectonic history will be hard to understand for non-geologist readers, because a lot of prior geologic knowledge is assumed by the authors. There is no extended glossary, which would help non-expert readers. This is followed by an overview of the mineralogy (with a list of important mineral localities), of the paleontology (from the earliest stromatolites and oncolites to the hominids), of the hydrogeology and of the mining activities (both historic and current). (2) Geological attractions: These include landscapes (e.g., Kalahari, Namib Desert), mountains and mountain chains (e.g., Brandberg, Etendeka Plateau), but also unique locations from a geologic or mineralogic perspective (e.g., Kolmanskop, Dinosaur footprints, Hoba meteorite). These are described on almost 80 pages in 32 individual chapters with photos, profiles and excellent landscape drawings from the pen of CHRISTINE MARAIS, as well as references. Independent of the routes described elsewhere in the book, this chapter covers the most interesting geologic features. As before, the co-authors contribute in this chapter. (3) Excursions: 29 excursion routes, most along the main routes frequented by visitors to Namibia, are described in detail on almost 140 pages. The overview map shows that no region of the country was neglected. Each route description includes a black and white geologic map taken from the 1:2 million scale Geologic Map of Namibia and a stratigraphic column using the Namibian stratigraphic units, but unfortunately only very few references. The route descriptions always are in one direction only. Unfortunately, this means that the excursion chapters are very difficult to use if one travels in the opposite direction. It would have been useful if the text had oriented itself by mile markers or at least given distances to allow more independent orientation.
The great achievement of Schneider and her co-authors is that they have presented Namibia’s geology for the first time in a concise English-language guide. Every visitor to Namibia, who is interested in geology, should carry the Roadside Geology in their luggage. The great achievement of Schneider and her
co-authors is that they have presented Namibia's geology for the first time
in a concise English-language guide. Every visitor to Namibia, who is
interested in geology, should carry the Roadside Geology in their luggage. The
geologic information takes into account the most recent state of scientific discussion. The co-authors ensure a uniformly high standard for the discussion of all stratigraphic units and all geologic regions. It is all the more unfortunate that the co-authors do not include a Quaternary geologist or geomorphologist, even though more than half the country is covered by the surficial deposits of the Kalahari and Namib Deserts (p. 9). The discussions of the Quaternary and of imposing geomorphologic features (Great Escarpment, peneplains, Namib Sand Sea, Kalahari dunes, Etosha Pan, inselbergs, etc.) are severely lacking. Readers interested in Quaternary geology and geomorphology will be disappointed that important features such as the Clay Castle Silts of the Hoarusib River, the Amspoort Silts of the Hoanib River and the silt terraces of the Khowarib Gorge are not mentioned at all. The Homeb Silts of the Kuiseb River are mentioned (p. 149), but not explained in detail even though the Clay Castle Silts were featured on a Namibian postage stamp in a series on the geology of the country. Furthermore, the discussions of the impressive dune fields of the Kalahari desert, which supposedly formed between 20 and 16 ka BP (p. 79ff., 199-202, 206, 228), and which are invoked as evidence for an incredibly recent valley formation in the SW Kalahari (p. 202), do not reflect the latest state of knowledge. This also applies to the explanation of the abundant calcretes (p. 140, 227), as well as the ocean-derived sulphur deposits in the coastal Namib Desert (p. 247). The development of the river systems in the Etosha Basin (Fig. 8.8.1) does not match the description on p. 70. Recent surface exposure dates from the Namib peneplain illustrate the amazingly long timespans required for the formation of these peneplains, but they are not even mentioned in Roadside Geology. There are more examples for this lack of discussion of geomorphology and Quaternary geology. A new edition hopefully will bring improvements and additions. The Quaternary features are admired by many visitors to Namibia, and they are featured prominently on the front and back covers of Roadside Geology. Perhaps the photo volume Namibia - Eine Landschaftskunde in Bildern (HÜSER et al. 2001) can offer suggestions in this direction.
While the Cenozoic sediments and landforms define 50% of the surface area, hard rock geologists are more interested in the up to 2.6 billion-year-old rocks, the igneous intrusions, the basaltic lava flows of the table mountains, the mineral deposits and the tectonic features. For these users, the guide fulfills all expectations.
KLAUS HEINE, Regensburg