Arrange sentences A, B, C and D between sentences 1 and 6 to form a logical sequence.
1. A reptile becomes stuck in a swamp and dies.
A. Over great periods of time, the peat is compressed and turned to coal.
B. As the centuries pass and more vegetation accumulates, the deposit turns to peat.
C. Changes in sea level may cause the swamp to be flooded and layers of sand to be deposited on top of the peat.
D. Dead vegetation drifts to the bottom and covers them.
6. The reptile’s bones still remain within it.