Jon Trevelyan (UK)
This is an ambitious little field guide, which aims to allow amateurs to identify basic rocks and rock formations, for the first time, in a systematic way. I must admit that I sometimes find it difficult (and somewhat daunting) to identify the geology in front of me in the field. The professional geologists I know seem to rely on experience, intuition and an in-depth familiarity with the components of rocks, all of which are not available to me and other amateurs with little or no previous experience or knowledge but with a desire to identify rocks.
However, as the author says:
“… the main reason the world of rocks is so complex is that it is devoid of the concept of species, unlike the worlds of animals and plants. There are no straightforward, unequivocal methods for identifying rocks”.
Therefore, the intention of this book is to allow people like me to distinguish the relevant minerals, as it says:
“… using only careful observation, a magnifying glass, a pocket knife – and a bit of patience”.
In this respect, apparently there is currently no definitive and complete rock identification key for amateur geologists to use. Therefore, this book uses an approach that will be familiar to botanists, who use targeted questions paired with grids of possible answers, complemented with ‘loops’ that allow (in this instance) a rock to be correctly identified following different paths.
However, as the author admits, this can result in different search paths leading to very different rock types being placed next to one another in the same key category in this guide. Nevertheless, this is unavoidable because the path to the identification of your chosen rock cannot rely on generic criteria, as pointed out above, but must be based exclusively on observable properties.
The book is set out in three sections covering: the fundamentals, an identification key and an introduction to rock classification. It has more than 530 beautiful, full colour photographs, tables and diagrams of the fundamental characteristics, which display their mineral constituents, structures, textures, fossils and weathering patterns, and so on. The final part briefly covers rock systematics.
Overall, I think this may be well worth getting, as it might just turn out to be extremely useful and one day be a little classic. Who knows?
Jürg Meyer lives in Switzerland and is a professional geologist and licensed mountain guide, as well as a lecturer and author in connection with geology and the environment.
Rocks and Rock Formations: A Key to Identification (Princeton Field Guides), by Jürg Meyer, Princeton University Press, Princeton and Oxford (2021), 192 pages (paperback), ISBN: 978-0691199528.