The physical geography and geology of the estuary and Firth of Forth, Scotland

Author(s):  
Michael A. E. Browne

SynopsisThe Upper Palaeozoic bedrock, which is of sedimentary and volcanic origin, is briefly described. The origin of the Forth as a series of depressions in the bedrock surface probably owes much to erosion of a pre-existing Tertiary landscape during phases of Quaternary glaciation. The late Quaternary history of the area is described, relating the distribution of the sediments deposited in the Forth to climatic events and changes in relative sea-level. Since the acme of the last main glaciation about 20,000 years ago, late Devensian marine and estuarine sediments have been deposited on the underlying glacial till sheet at altitudes ranging from more than 120 m below O.D. to at least 46 m above O.D. Similarly, raised and buried beaches and their deposits occur at altitudes from 40 m above O.D. down to around 10 m below O.D. in the estuary. During the Flandrian, sea-level has fluctuated, reaching its maximum (about 11 to 15 m above O.D.) about 6500 years ago. The typical deposit of this period is the carse clay which forms a series of extensive, fertile raised mudflats around the estuary. The calcareous marine faunas of the carse clay and older deposits are outlined.


1996 ◽  
Vol 33 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Alan E. Taylor ◽  
Scott R. Dallimore ◽  
S. I. Outcalt

Five offshore drill holes northeast of Richards Island reveal permafrost conditions, which are interpreted in terms of the sea-level and paleoenvironmental history of the Canadian Beaufort Shelf. The top of ice-bonded permafrost lies 76–88 m below the seabed within 12 km of the shore, 11 m below the seabed 20 km offshore, and at 60 m some 50 km offshore. The base of permafrost is 500 m to over 700 m deep. Temperature–depth gradients are negative or nearly isothermal, and permafrost is degrading. Geothermal modelling of the temperatures and permafrost observations indicates that the sites were subaerially exposed throughout most of the Wisconsinan, and during the early Holocene. Three sites 2–10 km from the present shoreline experienced inundation at 3.5–4.0 ka. These times support dates of marine transgression predicted by the sea-level curve, but the sites may have been occupied by thermokarst lakes prior to transgression. In contrast, the site 20 km offshore with shallow ice bonding was inundated about 0.4 ka; this area may have persisted as an island until recently. Shoals observed nearby may be analogues of this process, being outliers that are now being eroded below sea level. Marine transgression occurred about 6 ka some 50 km offshore.



1991 ◽  
Vol 6 (5) ◽  
pp. 609-619 ◽  
Author(s):  
Niall C. Slowey ◽  
William B. Curry


1990 ◽  
Vol 102 (7) ◽  
pp. 969-982 ◽  
Author(s):  
STEVEN L. RENEAU ◽  
WILLIAM E. DIETRICH ◽  
DOUGLAS J. DONAHUE ◽  
A. J. TIMOTHY JULL ◽  
MEYER RUBIN


1985 ◽  
Vol 4 (1) ◽  
pp. 7-22 ◽  
Author(s):  
KAJ STRAND PETERSEN


Author(s):  
T. F. Pedersen ◽  
R. François ◽  
L. François ◽  
K. Alverson ◽  
J. McManus


1957 ◽  
Vol S6-VII (1-3) ◽  
pp. 83-90
Author(s):  
Rene Battistini

Abstract A preliminary report on Quaternary shore lines and dune systems of the extreme southern part of Madagascar. Consolidated beach deposits three meters above present sea level are attributed to a stillstand (here named the Karimbolian) which occurred prior to the pre-Flandrian regression. This three-meter level acts as a marker zone for identifying periods of dune formation. Present knowledge of the Quaternary history of the region is summed up in a table correlating climates, cycles of erosion and continental sedimentation, shore lines, and phases of dune formation.



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