As a past student of Australian ecology, I have come to understand the immense gulf in character between the soils of Australia (and sub-Zambezian Africa) on the one hand and those of the rest of the (non-equatorial) world on the other. Owing to the fact that they have not been rejuvenated by mountain-building or glaciation, soils in Australia and sub-Zambezian Africa contain orders of magnitude less bioavailable phosphorus than other soils outside equatorial regions. The result is unique floral adaptations through features like proteoid roots and a
vastly different hydrology
that requires immensely larger storages to regulate rivers.
Serpentine soils, which are found in specialised geological situations whereby dense rocks are forced to the surface by plate collisions, are in this context interesting because they provide the only example in other temperate regions of soils comparably infertile to typical soils in Australia and sub-Zambezian Africa. Serpentine as a rock has been known since classical times, but the study of its peculiar mineralogical properties dates only from the era of systematic botany beginning around two hundred years ago. At the time, the most accessible examples of serpentine were to be found in the Appalachian Mountains of eastern North America, and it is on this that Dann focuses in "Traces on the Appalachians".
The book consists of a history of the serpentine "barrens" (so called because of their lack of vegetation even in a wet climate) of such states as Pennsylvania, Virginia and the Carolinas. Beginning with surprisingly good details of the Native American occupation of the area, he traces the history from that time up to when the "barrens" were first recognised as unique floral communities tightly related to their unique geology. Dann then looks at the history of the mining of serpentine lands, in a reverse chronological manner that manages to be very effective at showing how serpentine has been recognised through both history and prehistory. He then looks at the study of the evolution of serpentine from
Darwin
to
Wegener
and beyond, showing how ophiolites (the group of rocks which includes serpentine) arise as part of plate collisions (as I noted above). The last part looks at the broader history of ophiolites and how they are connected to findings that part of Newfoundland protruded above a relatively thin ice sheet during the Quaternary.
All in all, though this part is not as well-done as the others, it is still informative, and adds further to an impressive book that perhaps should have focused more on the problems serpentine soils pose for agriculture and other land uses owing to their low fertility and erosion risk - but otherwise comes definitely recommended.
