|
Discussion |
1 1School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK (e-mail: a.hallam@bham.ac.uk)
2 2School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK
3 3Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK (e-mail: stephen.hesselbo@earth.ox.ac.uk)
4 4Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, USA
5 5Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
| The first 250 words of the full text of this article appear below. Images appear only in PDF or full-text views. |
Tony Hallam & Paul Wignall write: we welcome the paper by Hesselbo et al. (2004) for its thorough description and careful evaluation of the environmental significance of an important group of system boundary strata, but beg to take issue on a number of key points.
(1) Most importantly, while we agree with the evidence of a regressive phase within the Cotham Member, we maintain in marked contrast to their opinion that there was also a sharp regression followed by a rapid transgression at the junction of the Langport Member (of the Lilstock Formation) and Blue Lias. It is pertinent before discussing the evidence in SW England further to take into account the broader European context (Hallam & Wignall 1999, with many relevant references cited therein). The evidence is especially clear in Germany where there was extensive shallowing in the latest Rhaetian marked by progradation of sandstone over shales. In northern Frankonia (Bavaria) fluvial sandstones infill channels incised into late Rhaetian marine strata and are overlain by marine Hettangian. The sea-level rise in the earliest Hettangian (planorbis Zone) was evidently rapid, with the limit of marginal marine sandstones in the eastern part of southern Germany being pushed back at the expense of fully marine shales to the maximum extent achieved during the whole Hettangian Stage.
Both in the north and south of Europe a similar pattern of successive sea-level fall and rise can be inferred. A clear end-Triassic regressive pulse can be recognized in the Danish Basin,
This article has been cited by other articles:
 |
|
 |
|
  J. D. RADLEY, R. J. TWITCHETT, L. MANDER, and J.C.W COPE Discussion on palaeoecology of the Late Triassic extinction event in the SW UKJournal, Vol. 165, 2008, pp. 319-332 Journal of the Geological Society, 2008; 165: 988 - 992. [Full Text] [PDF]
|
|
|
|
|
|
T. H. Sheppard Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK Journal of the Geological Society, 2006; 163: 595 - 606. [Abstract] [Full Text] [PDF]
|
|
