Britannica
Sources used in this answer
How does a horst differ from a graben?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
tectonic basins and rift valleys
Escarpments of the Great Rift Valley rising above the plain north of Samburu Game Preserve, central Kenya. Beisa oryxes graze in the foreground.
Horsts and grabens are elongate crustal blocks defined by their vertical movement relative to surrounding areas, caused by faulting under lateral tension.1
The primary differences between them are:
- Direction of Movement: A horst is a block that has been raised, while a graben is a block that has been lowered.1
- Fault Orientation: Both are bounded by steeply dipping normal faults. However, the faults forming a horst generally dip away from each other, whereas the faults forming a graben generally dip toward each other.12
- Topographic Expression: Horsts often form elevated features such as mountain ranges, like the Vosges Mountains. Conversely, grabens form depressed segments or valleys, often referred to as rift valleys, such as Death Valley or the Jordan–Dead Sea depression.12
These structures frequently occur together in regions like the Basin and Range Province, creating a characteristic landscape of alternating raised and lowered blocks.2