 |
 |
 |
 |
 |
 |
 |
 |
 |
| HOME | FOSSILS PAGE |
LAST DRAWER |
LAST IMAGE |
NEXT IMAGE |
NEXT DRAWER |
MORE TEXT |
IMAGE INFO |
LINKS |
|
|
|
|
|
|
|
|
|
| HOME | FOSSILS PAGE |
LAST DRAWER |
LAST IMAGE |
NEXT IMAGE |
NEXT DRAWER |
MORE TEXT |
IMAGE INFO |
LINKS |
......
set: fossils // series: chalk // picture: COCCOLITHS
This scanning electron micrograph (SEM) shows how important organisms can be in forming sediment. The high resolution image shows a fractured surface of a fragment of Upper Cretaceous chalk. The chalk is composed mainly of small elliptical 'scales' or platelets or fragments of these, each fragment or platelet element being a single calcite crystal. The platelets (coccoliths, average 7 microns in diameter) once overlapped to form an external skeleton (coccosphere) which surrounded the spherical cells of tiny plankton (diameters 15-100microns) which lived in the surface waters of the ancient chalk sea. . . . . more