Environmental Engineering Reference
In-Depth Information
Plate 12.3
Rhythmically bedded alternating layers of organic-
(dark) and carbonate-rich (light) mudstones at Kimmeridge
Bay, Dorset, deposited in a shallow Jurassic marine basin
140 Myr ago, retain their original depositional bedding
structures. Compare these with the metamorphosed structures
in Colour Plate 11 between pp. 272 and 273.
Photo: Ken Addison.
movement, driven by tectonic processes or climate change, alters the size of terrestrial
and oceanic basins and influences terrestrial erosion rates. Sedimentary onlap and offlap
sequences may indicate episodes of marine
transgression
or
regression
respectively
and/or changes in sediment supply.
Particular reference is made here to biogenic and chemical rocks, which feature less in
the review of clastic sedimentation in later chapters. Living organisms form
biogeomorphological
facies and landforms such as wetlands, salt marshes and coral reefs,
and burrowing organisms disturb soft sediments (
bioturbation
). Dead organic matter
retains much of its life form as whole
fossils
in shell
