东非大裂谷所在位置从地质构造上说是地堑还是断层构造带？记得以前对此就有疑问，但一直没能查个明白。今天终于弄明白了——东非大裂谷所处位置其实是一个地堑。
东非大裂谷的英文名称叫做the Great Rift Valley，其中rift valley就是地堑的意思。其实以前就知道东非大裂谷的英文名称叫the Great Rift Valley，当时就在想为什么要加一个rift呢？用the Great Valley不就得了吗？现在看来加上一个rift是另有意思的。
以下为查到的相关文字材料：
The subsidence of rock resulting from two or more parallel rocks moving apart is known as a graben. When this happens on a large scale, with tectonic plates moving apart, a rift valley is created.
Volcanic valley formed 10–20 million years ago owing to rifting (major subsidence through faulting) of part of the Earth\'s crust, and running about 8,000 km/5,000 mi from the Jordan Valley through the Red Sea to central Mozambique in southeast Africa. For most of its length the Rift Valley has a width of some 60 km/35 mi and, in highland areas especially, is bounded by inward-facing escarpments with a height which often reaches 500–1,000 m/1,500–3,000 ft. It is marked by a series of lakes, including Lake Turkana（图尔卡纳）, and volcanoes, such as Mount Kilimanjaro（乞力马扎罗山）. The rift system associated with the Rift Valley extends into northern Botswana, with geological faults controlling the location of the Okavango Delta（奥卡万戈三角洲）.
以下为查到的奥卡万戈三角洲的一幅地图：
