Three or four stars for most people but a solid five stars for two sorts of persons:
(1) Any geologist or scientist in a related field, or more importantly
(2) Any reader among the 95% of us who thinks that science is a collection of facts
But not one per cent of one per cent of group 2 will touch this, because it's about (OMG): "science, a collection of facts".

"The Great Devonian Controversy" relates the discovery of and scientific controversies surrounding the identification of the Devonian period and geologic system. It happened primarily in England from about 1834 to 1843. The Devonian period lasted from about 420 to 360 million years ago, when fish first appeared and plants began colonizing the land.

The geologists fell into three camps: gentlemen geologists whose wealth enabled them to do geology full-time as they pleased, poorer geologists working for the government primarily to locate coal deposits more cheaply but pursuing more general geology along the way, and local amateurs who knew just what was valuable in their regions and exactly where to find it. The Devonian and other periods and systems that they identified as meaningful are still in use.

As for general results, they confirmed the suspicion that geological systems are uniquely identifiable and are correlated among continents. And they demonstrated that fossil evidence is more reliable than rock type for correlating strata, consequent to their realization (with paleontologists' help) that fossils tend to be unique in any system although layers of the same age may differ in rock type in different regions.

The rationale for 494 pages on this short period is to show how science works up close. Everyone should know this.

The "Controversy" of the title reflects some of the relations among the geologists, who interact in part in gentlemanly discussion and in part with hammer and tongs (figuratively speaking). It is an example of the usual style of constructive dialectic essential to scientific inquiry.

Two particular aspects of the controversy are worth mentioning as comprising a general scientific style. One is the considerably contingent quality of the various revelations. Another is the non-Kuhnian style of the synthesis, unless seen at a distance darkly. Kunhian paradigm shifts seem to reduce in proportion as historical magnification increases.

By the way, the Devonian system is present but is poorly characterized around Devon: another contingency.

The book is well researched, documented and written, even if it has more geological and other detail than the layman may want. The author sums up and then summarizes the summary, yikes. Then he considers various general viewpoints, including the philosophical (like realist vs. constructivist) and rhetorical. The thinking is clear and commendable. ( )