Page 191 - Sedimentology and Stratigraphy

178 The Marine Realm: Morphology and Processes

relatively slow and a firmground forms. The char- Sedimentary structures can be used as indicators of
acteristic ichnofacies of firmgrounds is Glossifungites the effects of tidal currents, waves in shallow water
(Ekdale et al. 1984). At even slower rates of sedimen- and storms in the offshore transition zone. Further
tation complete lithification (18.2) of the sea floor clues about the environment of deposition are avail-
occurs with the formation of a hardground typified able from body fossils and trace fossils found in shelf
by the ichnofacies Trypanites (Ekdale et al. 1984). sediments. More details of the coastal, shelf and deep-
Recognition of hardgrounds and firmgrounds is water environments are presented in the following
particularly important in the sequence stratigraphic chapters.
analysis of sedimentary successions (Chapter 23).

FURTHER READING
11.8 MARINE ENVIRONMENTS:
SUMMARY Bromley, R.G. (1990) Trace Fossils, Biology and Taphonomy.
Special Topics in Palaeontology 3, Unwin Hyman, London.
The physical processes of tides, waves and storms in Johnson, H.D. & Baldwin, C.T. (1996) Shallow clastic seas.
the marine realm define regions bounded by water In: Sedimentary Environments: Processes, Facies and Strati-
depth changes. The beach foreshore is the highest graphy (Ed. Reading H.G.). Blackwell Science, Oxford;
energy depositional environment where waves break 232–280.
Pemberton, S.G. & MacEachern, J.A. (1995) The sequence
and tides regularly expose and cover the sea bed.
stratigraphic significance of trace fossils: examples
At this interface between the land and sea storms
from the Cretaceous foreland basin of Alberta, Canada.
can periodically inundate low-lying coastal plains
In: Sequence Stratigraphy of Foreland Basin Deposits (Eds
with seawater. Across the submerged shelf, waves, Van Wagoner, J.C. & Bertram, G.T.). Memoir 64,
storms and tidal currents affect the sea bed to different American Association of Petroleum Geologists, Tulsa,
depths, varying according to the range of the tides, OK; 429–476.
the fetch of the waves and the intensity of the storms. Seilacher, A. (2007) Trace Fossil Analysis. Springer, Berlin.