Hartman (geology and geological engineering, U. of North Dakota, Grand Forks) introduces this badlands region as "...the most sampled source of geological and paleontological data used to evaluate changes in nonmarine faunas and flora across the Cretaceous-Tertiary (K-T) boundary." Since research in the 1980s on this area of western North Dakota, South Dakota, and east- central Montana to test the impact theory of dinosaur extinction, Hell Creek Formation has been a hub for K-T boundary event studies. (It yielded the T-Rex named "Sue.") Nineteen chapters review new data on issues concerning the age of the Hell Creek fossil exposures, dinosaur assemblage, and mammalian and plant evolution. The final chapter is a synthesis of the others. Includes site illustrations and data tables. Annotation c. Book News, Inc., Portland, OR (booknews.com)