One of the most provocative tectonic models advanced in recent years contends that the eastern edge of the North American continent collided with the southern South America (Argentina) during the Grenville orogeny in Late Precambrian-early Paleozoic time (750-550 Ma). This idea has major implications for the evolution of the earth in terms of tectonics, climate, and organic distribution. This proposal outlines plans to test this model by examining critical shear zones in Argentina that are thought to have facilitated this major collision. The project will initially concentrate on gathering kinematic data on shear zones in the Pampean Terrane in order to determine movement histories and metamorphic conditions during movement.