MONTEZUMA CASTLE, _a pueblo ruin in the Verde River valley of central Arizona, has no connection with the Aztec emperor whose name it bears. The name was given by early settlers in the Verde Valley in the belief that the striking 5-story ruin with its 20 rooms had been built by Aztec refugees, fleeing from central Mexico at the time of the Spanish conquest. It follows naturally that the small lake inside a hill 7 miles away should be named Montezuma Well. While the story of the flight is known to be false, the names remain._ The aboriginal builders of the Castle left no records, but they did leave broken pottery, trash, and other debris of their everyday life. The analysis of this material tells us that these people, whom we call Sinagua (see glossary), were peaceful farmers who occupied this area from the 1100’s until the 1400’s; that they were similar in physical type to many of today’s Pueblo peoples in northern Arizona and New Mexico; and that they differed somewhat in their daily life from their neighbors in the desert to the south and in the mountains and plateaus to the north. This is their story, and we hope that it can take you back in your mind’s eye to the time when their fingers left marks as they plastered the walls of Montezuma Castle, and to the time when their fires left the smoke deposits you still see on those walls. But this story must begin with the land itself.... _Forces of Earth_ Montezuma Well and the cave in which Montezuma Castle is built both exist today because of a series of events that began over 1 million years ago. A flow of lava coming from the Black Hills at the south end of the Verde Valley closed the narrow canyon through which the Verde River then ran. This formed a natural dam and the river backed up against it to form a lake. Other rivers farther upstream added more water, and carried in large quantities of dissolved limestone from the higher elevations which they drained. [Illustration: _Bird’s-eye view of Verde Valley landscape and geology._] Consequently, in late Pliocene times (perhaps 1 million years ago), the Verde Valley was covered by a shallow lake or marsh 25 to 40 miles long and 12 to 15 miles wide. Its extent can be determined by noting the boundary between the light-colored sedimentary limestone and the dark basalts or the red sandstone marking the old shoreline. This light-colored rock was redeposited from the original limestone beds upriver and, therefore, the entire formation is almost devoid of fossils. Well preserved cougar tracks, however, imbedded in a slab of limestone, were found a few miles north of Montezuma Castle near Cornville, Ariz.