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Jürg Meyer, born in 1954, holds a doctorate in geology, should know. He is an independent consultant, speaker, excursion leader, mountain guide, trainer and author of successful Swiss geology books. The domain of his website, www.rundumberge.ch, is also understandable from this comprehensive approach. Before two of his works are presented, a brief look at the CV of the passionate mountain enthusiast.
After completing a diploma at the University of Basel on the construction of a Jura fold (1979), he received his doctorate in 1983. The topic of his dissertation, “Mineralogy and Petrology of Allalingabbros”, will continue to occupy him 40 years later. After a few permanent positions, such as at the University of Bern and the SAC, which stands for Swiss Alpine Club, where he worked as head of the environmental department, the step into self-employment came in autumn 2007. From now on, the Swiss mountains will be his topic. He knows the Western Alps, including the Swiss portion of the Southern Alps in Ticino, like the back of his hand. Enough of the geological topography!
The book Rocks of Switzerland - the field guide was published in 2017. The second, revised edition has been available since 2022 and is presented here. Like an accompanying text, the foreword (page 7) records what the book wants and can do. It wants to give stone lovers, amateur geologists etc. something “concrete and tangible about the rocks of Switzerland”. It also makes it clear what it does not want and cannot do: it is "neither a textbook on rock science nor on Alpine geology." Also the question “How to use the book?” is discussed at the beginning. The book's division is based on sites that are divided into 16 geological zones, which can be found in the front end of the book as a simplified geological map. Here the location of a rock can be quickly located.
But before we get down to the nitty-gritty of "The Rock Portraits" (page 109), all sorts of geological equipment, i.e. basic knowledge, is necessary. Meyer is by no means skimpy and conveys the necessary basic geological knowledge, including mineralogy and paleontology, in an understandable manner. Part I on pages 13 to 82 deals with general geological principles. What follows is an easy-to-read, richly illustrated introduction to general geology, as it is read at the beginning of studies at all geological institutes in the world. This is followed by Part II, "The formation of the Alps and their rocks", in other words: a compact outline of the geology of Switzerland.
The structure is based on the 16 rock zones mentioned at the beginning, starting from the north (Jura Mountains) to the south (Mesozoic sedimentary rocks of the Southern Alps). Within the zones, the description is based on the lithology (= type of rock) or the formation or complex (= rock unit that can be easily defined in the terrain). Introductory texts about the zones explain the formation and position of the rocks within the Swiss mountains.
The individual portraits span one to two pages of images, each showing a landscape image and a rock image. Information about the rock class (sedimentary rock, metamorphite, igneous rock) is given as well as information about age, components, hardness, thickness (= thickness of the rock occurrence in nature), use or comments on variability, relatives and confusion. In some cases, information about inclusions and fossils or climbing properties can be found.
Individual topic boxes, for example about river pebbles (page 181), alpine fissures and fissure minerals or boulders, complement the lithological journey. Glossary (page 433) including a bibliography in the appendix and web tips at the end prove to be useful.
Four pages were not enough for rock number 92, the Allalin metagabbro, so a separate book would have to be produced in 2024. The green rock, which is also known in Switzerland as "Saussurit-Allalin-Metagabbro" or simply as "Smaragdite-Gabbro", was raised to the pedestal as "Allalin-Gabbro from the Valais Alps" and comprehensively described, commented on and illustrated on 236 pages as the "most beautiful rock in the world". First of all, this predominantly green, mottled rock, like granite, is a deep rock, i.e. it comes from a magma melt that has solidified in the earth's crust. Since pressure and temperature affected the rock body, which is now 2 x 1 x 1 kilometer in size and can be found at over 3,000 meters above sea level in the south of Switzerland around ten kilometers east of Zermatt, through the overlay of thick layers of rock, the gabbro was changed. A metagabbro was created as a metamorphic rock (metamorphite). This is to correct the various terms in the nomenclature. And here lies the key to its beauty, because like no other rock, the Allalin gabbro, which consists of no fewer than 46 minerals (page 132ff.), 17 of which can be seen with the naked eye or magnifying glass, has a very eventful history.
Under the title "Up, over, down, over and back up again", Meyer describes from page 106 the geological history of the rock body, which was formed around 164 million years ago (Mezoo-Mezoo/Jurassic period) from a molten rock in the lower crust of what was then the Adriatic microcontinent. As a result of plate tectonic processes around 44 million years ago, the rock reached depths of around 90 kilometers, which corresponds to a pressure of 26 kilobars and a temperature of 600 degrees Celsius. Geologists speak of the high-pressure metamorphism that the rock experienced.
During the slow rise from the depths, further overprinting (450 to 500 degrees Celsius) occurred around 38 million years ago. This metamorphosis/transformation primarily affected the edge of the rock body, therefore the term "metagabbro" is justified. The result is numerous new mineral formations, which today - now that the rock is located in high alpine regions thanks to mountain formation - can be seen in a colorful mineral diversity, in the truest sense of the word.
Such a complex history of a rock, with a colorful, very attractive variety of minerals, which is simply beautiful to look at and which fascinated and convinced people from the Stone Age who used the Allalin gabbro for tools. Added to this is the spread of larger and smaller boulders as boulders through Ice Age glaciers, so that the Allalin gabbro can also be found in the Swiss plateau and has a fan base there too.
Conclusion: Rocks of Switzerland - The field guide fascinates with its comprehensive lexical approach. The most beautiful rock in the world - The Allalin gabbro from the Valais High Alps is a subjective approach as it ranks on the podium in the beauty ranking. But the high honors for the rock, which presents itself in the best aesthetic form, with its unique history, are understandable due to the excellent, richly illustrated and well-founded presentation. (Thomas Hofmann, March 7, 2025)