Q 01/05

Roughly how long is the Great Rift Valley, from northern Syria to Mozambique?

A) 650 km

B) 2,500 km

C) 6,500 km

D) 15,000 km

Answer · why

C) 6,500 km

Geologists now prefer the term Afro-Arabian Rift System for the structures beneath it.

Q 02/05

Which British geologist introduced the term Great Rift Valley in 1896?

A) Charles Lyell

B) Joseph Thomson

C) Louis Leakey

D) John Walter Gregory

Answer · why

D) John Walter Gregory

He built on Austrian geologist Eduard Suess's idea of a linked set of features from Syria to Mozambique; the eastern branch is named after him.

Q 03/05

Gregory defined a rift valley as a linear valley with steep, almost vertical sides that has done what?

A) Been carved out by a glacier

B) Been blasted open by a volcano

C) Dropped between a series of faults

D) Been eroded by a great river

Answer · why

C) Dropped between a series of faults

He visited central Kenya in 1893 and 1919; his 1896 book The Great Rift Valley is a classic.

Q 04/05

The East African Rift is a boundary where the African plate is splitting in two. What are the two halves called?

A) Antarctic and Australian

B) Eurasian and Anatolian

C) Arabian and Indian

D) Somali and Nubian

Answer · why

D) Somali and Nubian

Three microplates, Victoria, Rovuma and Lwandle, sit within the system.

Q 05/05

At what rate are the two sides of the East African Rift pulling apart?

A) 8-9 mm per year

B) 2-3 cm per year

C) 8-9 cm per year

D) 80-90 cm per year

Answer · why

A) 8-9 mm per year

Marine geologist Kathleen Crane suggests eastern Africa could eventually separate from the mainland, but over tens of millions of years.