Positing an enormous volcanic explosion at the end of the Permian period would explain the presence of a buried crater, account for the presence of the element iridium (originating deep within the earth), and the presence of quartz having been shattered by high-impact shock waves.

About 5 million acres in the United States have been invaded by leafy spurge, a herbaceous plant from Eurasia with milky sap that gives mouth sores to cattle, displacing grasses and other cattle food and rendering rangeland worthless.

Next month, state wildlife officials are scheduled to take over the job of increasing the wolf population in the federally designated recovery area, the number of which will however ultimately be dictated by the number of prey in the area.

Tides typically range from three to six feet, but while some places show no tides at all, some others, such as the Bay of Fundy, have tides of at least thirty feet and more.

To attract the most talented workers, some companies are offering a wider range of benefits, letting employees pick those most important to them.

The English physician Edward Jenner found that if experimental subjects were deliberately infected with cowpox, which caused only a mild illness, they are immune from smallpox.

Employing many different techniques throughout his career, Michelangelo produced a great variety of art works, including paintings, for example, in the Sistine Chapel, to sculpture, for example, the statue of David.

Between 14,000 and 8,000 B.C. the ice cap that covered northern Asia, Europe, and America began to melt, uncovering vast new areas that were to be occupied by migrating peoples moving northward.

Researchers now regard interferon as not a single substance, but it is rather a biological family of complex molecules that play an important, though not entirely defined, role in the immune system.

Cost cutting and restructuring has allowed the manufacturing company to lower its projected losses for the second quarter, and they are forecasting a profit before the end of the year.