The book is a compilation of locations in the Maryland, Delaware, and Washington DC area that can be visited to see the geology of these sites. The author appears to have first hand experience and a strong understanding of geological history. There are directions and pictures as well as many maps showing geological historical formations. I found the book interesting but it is likely best used as a reference when visiting these areas. I think that the sections that covers more general and basic information could be expanded to make the book more interesting to a larger audience. I wish I had a stronger knowledge of geology so that it would have made more sense to me. I am an engineer with strong physic, chemistry, and biology background. ( )

The Roadside Geology series keeps getting better and better. This is not to say that the early books weren’t good, but the printing technology of the time limited them to two color maps and drawings and a few black and white halftone illustrations. This volume has full color maps and/or photographs on almost every page. I’m very favorably impressed by the effort of author John Means; he’s a retired community college teacher, and presumably had the leisure to explore every country road in the study area; a full professor at a four-year university would have been under too much publish-or-perish pressure to devote this much effort. (Community college historian Jim Miles did a similar project with his series of American Civil War guidebooks).


The initial discussion of regional geology alone is easily worth the cover price. The historical geology of the Eastern Seaboard is really complex, with four orogenic events (Proterozoic Grenville, Ordovician Taconic, Devonian Acadian and Pennsylvanian Alleghanian) more or less mashed together (Oh, and there’s a Triassic failed rift arm and a couple of island arc microterranes in there, too). Means provides the best illustrations I’ve ever seen of how these fit together and the residue they left behind in local geology (I’m also less critical of North American geologists who failed to recognize plate tectonics for so long; in fact, I’m surprised that the geology is decipherable at all).


Road logs for western geology have the advantage that there’s a lot of rock to see and highway traffic is relatively light. Applying the same techniques to eastern geology would probably get you rear-ended by a texting teenager pretty quickly, and explaining “Officer, I was driving slowly because I was looking for the contact between the Sugarloaf Mountain Quartzite and the Antietam Formation” would probably be met with disapprobation. Thus, most of the book takes you to various parks, where you get out of your car and walk to see the rocks. Now and then there’s a road, railroad, or canal cut you can look at. I’m a little disturbed when Means sometimes suggests you walk along active railroad lines to view rock cuts; before I retired I had to take an annual railroad safety refresher course, which often included color photographs of the results of human/train interaction (not to mention being involved in cleaning up after a couple such incidents). Another disappointment (not Means’ fault, though) is that the 6th largest asteroid impact crater on the planet is just east of the tip of the Delmarva Peninsula – and there’s nowhere you can go to see any evidence of it on the surface.


It’s also not Means’ fault that the Maryland and Delaware Geological Surveys can’t agree on rock unit names; this results in some minor problems when geology crosses state lines (for example, see the book cover, where mapped formations sometimes have suspiciously linear boundaries).


There’s an extensive bibliography; unfortunately a lot of the referenced works are quite old since the geology of the area was “settled” a long time ago (as opposed to the interpretation of that geology). You could probably spend your life doing interesting weekend trips based on chapters from this guidebook. ( )