A cohort is a group of people who share a common characteristic or experience within a defined period (e.g., are currently living, are exposed to a drug or vaccine or pollutant, or undergo a certain medical procedure).
A rift valley is a lowland region formed by the interaction of Earth's tectonic plates. This small rift valley has a typical formationâlong, narrow, and deep. It was formed by the Thingvellir rift, where the North American and Eurasian tectonic plates are tearing, or rifting, apart over a hotspot on the island of Iceland.
1. Great Rift Valley - (geology) a depression in southwestern Asia and eastern Africa; extends from the valley of the Jordan River to Mozambique; marked by geological faults. geology-a science that deals with the history of the earth as recorded in rocks.