Researchers who study the fossil record are seeking to determine whether the impact made by a comet or meteor really did decimate up to half of the life on this planet at the end of the Cretaceous period. Questions whether the extinction of plant and animal life was abrupt, started before the impact, or was a gradual change. (KR)

The islands of western Lake Erie are rock-bound isles that abound in rocky outcrops and quarries. The rocks of these islands are of two distinct types, Silurian dolomites and Devonian limestones. The dolomites, exposed in the Bass Islands and Sister Islands are virtually devoid of fossils. Conversely, the limestones of Johnson Island, Marblehead,…