In 1992 the researchers returned to the Aramis area and focused their attention on sediments occurring between two volcanic ash horizons, the Daam Aatu and Gàala tuffs, which were dated to 4.4 million years ago.
The sampling stations in the Whittard Canyon were situated on an interfluvial area covered in fine sediments in between two upper NE branches (Fig. 1).
The rocks that entombed the partial remains of the whale (Messapicetus gregarius, depicted in an artist's reconstruction, above) accumulated as sea-floor sediments between 8.9 million and 9.9 million years ago, other fossils in the rocks suggest.
These sediments are sandwiched between two clay beds: the lower one at a depth of 250-650 m; the upper one 10-40 m in thickness.
The contrasting composition in particulate matter of floor sediments in the two chambers, suggests that the Dinaledi Chamber was an isolated sedimentary environment at the time of deposition of Unit 3, with no or very limited transfer of sediment between the two chambers.
[ 70- 76] Briefly, this is a method that can be used to estimate the relationship between two measurements with proportional errors, in this case sediment under optimal conditions and sediment under daily practice conditions.
Likewise, erosion in a basin may be characterized by sediment yield, number of erosion events, duration of events, intensity of events, and time interval between two consecutive events.
There it is mostly theoretical, though he has a model made of two rotating aluminum plates with glacial sediments between them, which he describes as "rotating a bagel and seeing the cream cheese shear".
The fossils had been entombed in rocks laid down as seafloor sediments sometime between 25 million and 28 million years ago, says Daniel Ksepka, a vertebrate paleontologist who is now at the Bruce Museum in Greenwich, Connecticut.
