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.
Or, the plates may be pulling apart from one another; this is what creates a rift valley. East African Rift System. The African Rift, also known as the East African Rift System (or EARS), is actually a system of rifts created by the separating of the Nubian Plate and the Somalian Plate, which together comprise the African Plate of the African continent.