The New Mexico Geological Society does an annual field excursion to somewhere in New Mexico or adjacent states and publishes an accompanying guidebook; this one is for the 2010 field trip, to the Four Corners area (where the states of Colorado, Utah, Arizona, and New Mexico meet). The main feature is a “road log”; if you’re unfamiliar with that, it’s an automobile guide to the field trip area, with directions, mileage markers, and descriptions of the geology along the route and at stops.

The road log is accompanied by special papers with more detail on the history and geology of the area, including discussions of the Pictured Cliffs petroglyph site and Holocene geology of Chaco Culture National Historical Site. Of some interest is a paper by retired USGS geologist James Fassett, contending that the Ojo Alamo Sandstone in the area is Paleocene, contains dinosaur bones, and therefore dinosaurs survived the KPg extinction. Fassett argues that paleomagnetic and palynological data establish the Ojo Alamo Sandstone as Paleocene and dinosaur bones in the formation are pristine condition and therefore were not reworked from Cretaceous rocks. I don’t know enough about the geology and paleontology of the area to offer an opinion, other than Sagan’s maxim that extraordinary claims require extraordinary evidence.

Otherwise this is a typical NMGS annual field trip – although the authors caution that a lot of the trip is on Navajo land and therefore requires tribal permission for any specimen collection. ( )