Rift Valleys and Horsts are the results of

Rift valleys and horsts are primary landforms resulting from the process of faulting, specifically associated with extensional tectonic forces [c1][t2]. Faulting occurs when brittle crustal rocks fracture due to tectonic stress [t8]. A rift valley (or graben) is formed when a block of the Earth's crust is displaced downward between two parallel normal faults [c3][t7]. Conversely, a horst is an upthrown or elevated block of crust bordered on both sides by normal faults [c3][t7]. These structures are characteristic of divergent plate boundaries where the crust is being pulled apart or stretched [c3][t10]. While folding is associated with compressional forces and mountain building (orogeny), and mass movement refers to exogenic processes like landslides, faulting is the specific endogenic mechanism responsible for the creation of block mountains, grabens, and rift systems [c4][t2][t4].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 9: Divergent Boundary > Stage 2: Rift Valley Formation > p. 126
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 10: Types of Mountains > Dip-Slip Faults > p. 138
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Orogenic or Mountain-Forming Movements > p. 81
4. [4] https://education.nationalgeographic.org/resource/rift-valley/