Erratum to “The Albian-Cenomanian boundary at Eggardon Hill, Dorset (England): An anomaly resolved?” [Proc. Geol. Assoc. 120 (2009) 108-120]

Re-examination of the classic exposures of the Eggardon Grit (topmost Upper Greensand Formation) at Eggardon Hill, Dorset shows that the upper part of this unit has a more complex stratigraphy than has been previously recognised. The Eggardon Grit Member, as described herein, is capped by a hardground and associated conglomerate, and is entirely of Late Albian age. The hardground is probably the lateral equivalent of the Small Cove Hardground, which marks the top of the Upper Greensand succession in southeast Devon. The conglomerate is overlain by a thin sandy limestone containing Early Cenomanian ammonites. This limestone is almost certainly the horizon of the Early Cenomanian ammonite fauna that has previously been attributed to the top of the Eggardon Grit. The limestone is regarded as a thin lateral equivalent of the Beer Head Limestone Formation (formerly Cenomanian Limestone) exposed on the southeast Devon coast. The fauna of the limestone at Eggardon suggests that it is probably the age equivalent to the two lowest subdivisions of the Beer Head Limestone in southeast Devon, with a remanié fauna of the Pounds Pool Sandy Limestone Member combined with indigenous macrofossils of the Hooken Nodular Limestone Member. The next highest subdivision of the Beer Head Limestone in southeast Devon (Little Beach Bioclastic Limestone Member), equates with the ammonite-rich phosphatic conglomerate of the ‘Chalk Basement Bed’, which caps the Beer Head Limestone at Eggardon, and which was previously regarded as the base of the Chalk Group on Eggardon Hill.Petrographic analysis of the Eggardon Grit shows that lithologically it should more correctly be described as a sandy limestone rather than sandstone. The original stratigraphical definition of the unit should probably be modified to exclude the softer, nodular calcareous sandstones that have traditionally been included in the lower part of the member.Without the apparently clear evidence of unbroken sedimentation across the Albian-Cenomanian boundary, suggested by the previous interpretation of the Eggardon succession, it is harder to argue for this being a prevalent feature of Upper Greensand stratigraphy in southwest England. Correlation of the Eggardon succession with successions in Dorset and southeast Devon reveals a widespread regional break in sedimentation at the Albian-Cenomanian boundary. The sand-rich facies above this unconformity represent the true base of the Chalk Group, rather than the ‘Chalk Basement Bed’ of previous interpretations.Selected elements of regionally important Upper Greensand ammonite faunas previously reported from Shapwick Quarry, near Lyme Regis, and Babcombe Copse, near Newton Abbot, are newly figured herein.     

Dedication: Dr. Scott W. Nixon (1943–2012)

The availability of suspended sediments will be a dominant factor influencing the stability of tidal wetlands as sea levels rise. Watershed-derived sediments are a critical source of material supporting accretion in many tidal wetlands, and recent declines in wetland extent in several large river delta systems have been attributed in part to declines in sediment delivery. Little attention has been given, however, to changes in sediment supply outside of large river deltas. In this study, significant declines in suspended sediment concentrations (SSCs) over time were observed for 25 of 61 rivers examined that drain to the East and Gulf Coasts of the USA. Declines in fluvial SSC were significantly correlated with increasing water retention behind dams, indicating that human activities play a role in declining sediment delivery. There was a regional pattern to changes in fluvial sediment, and declines in SSCs were also significantly related to rates of relative sea level rise (RSLR) along the coast, such that wetlands experiencing greater RSLR also tend to be receiving less fluvial sediment. Tidal wetlands in the Mid-Atlantic, Mississippi River Delta, and Texas Gulf especially may become increasingly vulnerable due to rapid RSLR and reductions in sediment. These results also indicate that past rates of marsh accretion may not be indicative of potential future accretion due to changes in sediment availability. Declining watershed sediment delivery to the coastal zone will limit the ability of tidal marshes to keep pace with rising sea levels in some coastal systems.     

Penrose Conference — 2011 on Deformation Localization in Rocks: New Advances — Manish A. Mamtani (IIT,Kharagpur; Email: mamtani@gg.iitkgp.ernet.in)

News and Notes

Penrose Conference — 2011 on Deformation Localization in Rocks: New Advances — Manish A. Mamtani (IIT, Kharagpur; Email: mamtani@gg.iitkgp.ernet.in)     

International Earth Science Olympiad — 2011: A Report — R. Shankar (National Coordinator,Earth Science Olympiad; Email: rshankar_1@yahoo.com)

News and Notes

International Earth Science Olympiad — 2011: A Report — R. Shankar (National Coordinator, Earth Science Olympiad; Email: rshankar_1@yahoo.com)     

Training Programme on Major Tectonics and Lithounits in the Indus and Shyok Suture Zones of Ladakh Himalaya — M. Ram Mohan, (NGRI-CSIR,Hyderabad. Email: rammohan@ngri.res.in) and Sita Bora (Kumaun University,Nainital; Email: sitabora@yahoo.com)

News and Notes

Training Programme on Major Tectonics and Lithounits in the Indus and Shyok Suture Zones of Ladakh Himalaya — M. Ram Mohan, (NGRI-CSIR, Hyderabad. Email: rammohan@ngri.res.in) and Sita Bora (Kumaun University, Nainital; Email: sitabora@yahoo.com)     

Vol.34 No.1( Sum136 )

Review on the development of studies on the tectonic and orogen process of　orogenic belt,and discussing on some new key problems 　　………………………　　　 ZH ANG Guo- wei,DONG Yun- peng,YAO An- ping(9)　…………………………A primary research on some major issues of desertification 　　………………………　　　 WANG Min,YUE L e- ping,LI Zhi- pei,NIE H ao- gang(1 7)　………………………On the put out fire in coal field burning regions of Xinjiang　　………………………　　　 ZH AN…