- Extensive shallow depression called geosynclines develop on the earth’s surface.
Prolonged and extensive erosion occurs on the surrounding higher grounds.
![formation-of-fold-mountain-stage1.JPG](../Uploads/LessonImages/formation-of-fold-mountain-stage1.JPG)
- Sediments are deposited in the geosyncline forming thick layers. The weight of
the sediments causes subsidence of the geosyncline leading to accumulation of more sediment to great thicknesses.
![formation-of-fold-mountain-stage2.JPG](../Uploads/LessonImages/formation-of-fold-mountain-stage2.JPG)
- Further subsidence of the geosyncline triggers off compressional forces which cause sediments to fold. The folded layers of sediments in the geosyncline are thrust upwards to form fold mountains along the edges of the geosyncline due to closeness of the source of
force.
![formation-of-fold-mountain-stage3.JPG](../Uploads/LessonImages/formation-of-fold-mountain-stage3.JPG)