Most people do not think to observe geology from the sidewalks of a major city, but all David B. Williams has to do is look at building stone in any urban cente

Certain symbols abound in modern Western culture that are instantly recognizable: the cross signifies Christianity, the six-pointed Star of David is revered by

In 1866, Alexander Dunlop, a free black living in Williamsburg Virginia, did three unusual things. He had an audience with the President of the United States, t

In the final months of 1979, a city was born in dry forestland along the border of Cambodia and Thailand. It was a city of refugees. The Khmer Rouge had been re

Chaco Canyon, Canyon de Chelly, Mesa Verde, Hovenweep . . . For many, such historic places evoke images of stone ruins, cliff dwellings, pot shards, and petrogl