| 1 | Folds typically occur in anticline-syncline pairs. | |
| 2 | All synclines do not increase the return energy. | |
| 3 | Qiaotouhe syncline is one of the important coal-bearing syncline basin in Lianshao coalfield, Hunan. | |
| 4 | Beitai basin is a trapped syncline with its sedimentary sequence composed of volcanic sedimentary facies. | |
| 5 | The results provide theoretical basis for the anti-sliding design of the syncline rock structure. |