The timing of Acadian orogenesis in Maine is reassessed, on the basis of a new Silurian-Devonian time scale, new U/Pb and 40Ar/39Ar ages of Acadian plutons, new conodont and palynomorph ages of strata that constrain the age of deformation, and published information. This analysis shows that the Acadian deformation front migrated some 240 km (present distance) from southeast to northwest during a span of about 40 million years from Late Silurian to Middle Devonian time.

Description of three largely volcaniclastic units, which are assigned early Cretaceous age.

The nine papers in this volume cover the geology beneath Washington, D.C., Boston, Chicago, Edmonton, Kansas City, New Orleans, New York City, Toronto, and St. Paul/Minneapolis, and present methods of data gathering that could be used in most cities.