| 1 | The underground sediment of the Ganges Delta contains arsenic. | |
| 2 | Spirit found the plateau to be surrounded by deposits of opal. | |
| 3 | It is an actual three-dimensional structure, backfilled with sediment. | |
| 4 | And, at this point, traces of industrialization can only be found in sediments in Europe. | |
| 5 | The process of chemical and physical change in deposited sediment during its conversion to rock. |