THE Lizard district had long been famous as a field of geological research and controversy prior to the publication in 1912 of the Geological Survey Memoir on it, and on many of its petrological, structurah and stratigraphical problems there was scarcely a general consensus of opinion. This second edition, by the late Sir John Flett, one of the original authors, reveals him in the full maturity of his scientific judgment and mental vigour. It has been entirely rewritten after a re-examination of the area that, followed his retirement from the directorship of the Geological Survey in 1935. Many will visualize in these accounts of the cliffs and exposures "alongside the path leading from the hotel to the beach" that powerfully built figure with deliberate step and penetrating all-embracing eye.Memoirs of the Geological Survey of Great Britain England and Wales. Explanation of Sheet 359 : Geology of the Lizard and Meneage. By J. S. Flett and J. B. Hill. Second edition, by Sir John Smith Flett. Pp. xi+208+11 plates. (London : H. M. Stationery Office, 1946.) 2s. 6d. net.

Memoirs of the Geological Survey of Great Britain and of the Museum of Practical Geology: Mining records: Mineral statistics of the United Kingdom of Great Britain and Ireland for 1853 and 1854

Outside the limits of Middle Pleistocene glaciation, the river basins of Southern England contain long Cenozoic terrestrial sedimentary records. Of greatest importance are the river terrace sequences, which contain biostratigraphical and sedimentary evidence that testifies to the high-amplitude climatic changes of the Quaternary. However, trends in valley development cannot easily be accommodated within the framework of Quaternary climatic change. It is argued in this paper that episodic incision and terrace development result from uplift, a consequence of the interplay between continuing Alpine orogenic movements and erosion-driven isostasy. Using a simple linear model (height–age) an uplift rate of ca. 7 cm ka−1 is estimated for the terrace sequence in the upper Thames valley. This preliminary model is evaluated using the records of adjacent basins. © 1997 John Wiley & Sons, Ltd.

Uplift-driven valley incision and river terrace formation in southern England

Since the advent of North Sea exploration, a variety of new advances have been made in understanding basin dynamics and regional variations in structural style that are well-founded on the stratigraphy of the better known basins. New insights have also been made into the influence of Palaeozoic compressional and inversion tectonics on the structure of Mesozoic successor basins. This paper, based in part on these advances, offers a new, post plate tectonics, model for the structural and stratigraphic development of Mesozoic and Tertiary basins between mid-Norway and the Bay of Biscay. The tectono-stratigraphic evolution of this region can now be simply described in terms of a southward propagating ‘Arctic’ rift and a northward propagating ‘Atlantic’ rift. These rifts, formed by polyphase extension, remained largely separate entities until the Late Jurassic or Early Cretaceous. Thereafter, the rifts and their successor basins became a single entity represented by the Rockall Trough, Faeroe–Shetland Basin and More Basins only modified by later Cretaceous events and the Early Tertiary break-up of the North Atlantic and Norwegian–Greenland Sea. The ‘Arctic’ rift was initiated possibly as early as the Late Palaeozoic, nucleating on Caledonian and Late Devonian structures in the strike-parallel Caledonian terranes. Polyphase extensional events between the Permo-Triassic and Late Jurassic with intervening phases of passive subsidence resulted in rifts and basins of opposing polarity, sometimes superposed or offset, trending from the Barents Sea into the greater North Sea area. In contrast, the ‘Atlantic’ rift was probably initiated by rifting between North America and Africa in Late Triassic to Early Jurassic times. Its northward propagation was at first limited by the E-W and NE-SW Hercynian and Caledonian terranes of the British Isles and northeast Canada. The main subsequent major phase of extension initiated in the Late Jurassic and continuing through the Early Cretaceous progressively opened the North Atlantic from south to north through into the Bay of Biscay. The northward propagation of the Atlantic rift from Biscay into the Rockall Trough and Faeroe–Shetland Basin–More Basin completed the linkage to the Arctic rift possibly as early as the Late Jurassic and certainly by the Albo–Aptian. The ensuing rift, underlain by highly stretched continental crust, extended from the Barents Sea via the Voring Plateau, More Basin into the Rockall Trough. The subsequent Late Cretaceous history of the linked system of rifts is characterized by both extension and inversion of unknown origin. In the Early Tertiary, rifting associated with voluminous volcanism along the entire margin and on the scale of the Deccan Traps heralded the break-up by spreading of the Norwegian–Greenland Sea and the northern North Atlantic. A subsequent phase of rifting elevated the Jameson Land Basin of East Greenland exhuming major oil accumulations. In contrast, co-eval phases of inversion in the Voring Basin, More Basin and the Faeroe–Shetland Basin have had a positive impact on prospectivity. Inversion in the Celtic Sea is more probably related to the Pyrennean orogeny. The model of ‘Arctic’ and ‘Atlantic’ rifts offers a new and simpler predictive model of source and reservoir distribution. In the ‘Arctic’ rift, i.e. the North Sea, West of Shetland and offshore Norway–Greenland, volumetrically significant source-bed systems are confined to the Permo–Triassic, Toarcian, Middle and Late Jurassic. In the ‘Atlantic’ rift, between the Celtic Sea, Iberia and the Grand Banks, the major sources seem to be of Toarcian and Late Jurassic age. Cretaceous source beds are minor in the linked rift. However, the multiple phases of rifting and later burial or inversion history have severely affected the maturity of the Jurassic, although appeal to remigration is clearly necessary in the Faeroe–Shetland Basin. Distribution of the major reservoirs in both rifts can be best understood in relation to phases of rift propagation and subsequent subsidence. Thus, the early rifts and their immediate successor passive basins are characterized by shallow marine sedimentation. In contrast, the Late Jurassic-Early Cretaceous rifts were subject to stretching that resulted in initially deep marine environments and very thick infill of later Cretaceous sediments. Significant sand input to the linked rifts only began in the Early Tertiary as a result of the uplift and unroofing of Scotland that heralded the opening to the North Atlantic.

Palaeozoic to Tertiary rift and basin dynamics: mid-Norway to the Bay of Biscay – a new context for hydrocarbon prospectivity in the deep water frontier

Crustal uplift in southern England: evidence from the river terrace records

Abstract Hydrocarbons have been produced from the Carboniferous of the East Midlands since the 1920s. Some 30 discoveries have been made to date and although field sizes are generally small, the relatively low costs have made exploration and development an attractive commercial proposition. Many of the factors which contribute to success in the East Midlands occur in other basins in Northern England but have not produced significant hydrocarbon accumulations. This paper examines the key attributes of the intra-Carboniferous play and through an integrated regional geological framework contrasts the successful East Midlands oil province with the other Carboniferous basins of Northern England.

A regional assessment of the intra-Carboniferous play of Northern England

The Brassington Formation of the southern Pennines comprises a succession of sands, gravels and clays, the youngest beds of which contain Lower Pliocene fossil plants. These strata are generally considered to have foundered into the Carboniferous Limestone through solution subsidence mechanisms. The subsidencc cavities also contain detached marginal blocks of shale, which locally contain Namurian goniatites. Examination of the shale blocks from a number of widely separated localities has revealed that all contain Namurian spore assemblages, datable in some cases as E 2 (Arnsbergian) age. The contact between the shale blocks and oldest sands of the Brassington Formation is unconformable and, characteristically, the latter are seen to rest on zones of lilac-stained weathered shale, representing a pre-subsidence land surface. Evidence is presented which indicates that the Brassington Formation strata are conformable and that the succession represents a single cycle of sedimentation. Because of this conformable relationship it is inferred that this land surface is also of Lower Pliocenc (or Upper Miocene) age. A tacheometric survey of a well-exposed solution subsidence complex at the Bees Nest Pit, Brassington, has enabled structure contour maps to be made of key horizons in the succession. Laboratory tests have been conducted which have attempted to duplicate this structure and so indicate the probable subsidence mcchanisms. Results suggest that subsidence was gradual, with block-by-block removal of the host limestone, and took place in deep, steep-sided pipe-like forms. The depth of subsidence, and hence the elevation of the land surface prior to the deposition of the Brassington Formation, has been determined by estimating the thickness of limestone and Namurian shale which, as suggested by previous research work in the southern Pennines, was once present over the sites of the present subsidence masses. Subsidence can be shown to be of the order of 150–250 m, which implies that the Lower Pliocene land surface of the southern Pennines lay at about 450m O.D. Based on the evidence of the contemporary sea level, the presence of the Lower Pleistocene deposits of se England, and the sub-Neogene surface of the southern Pennines, a graph has been constructed which suggests broadly that Upland Britain has undergone a regular uplift since the main Alpine episode at a rate of about 1 metre in 15,250 years. In this light, the possible age of other well known planation surfaces is discussed.

The preservation of the Neogene Brassington Formation of the southern Pennines and its bearing on the evolution of Upland Britain

A dissolution pipe palaeokarst of mid-Pleistocene age preserved in Miocene limestones near Staszów, Poland

Abstract The best preserved denudation surfaces which are benched into the margins of the pre-Permian oldland massifs of western Britain and Ireland are those comparatively close to sea-level. Such surfaces have frequently been regarded as being of late Pliocene or Pleistocene age and of marine origin. Recent discoveries reviewed in this work reinforce a growing view that these low-level planations are much older and may be of terrestrial origin. Evidence from Wales and southwest England suggests that these little-modified planation elements represent landscapes some 15 Ma old. This paper reviews the palaeobotanical, sedimentological and geomorphological evidence for the close association of several bodies of non-marine Chattian and Miocene sediment and saprolite with some of the better known planation features. In these areas, the former vegetation comprised mixed coniferous/deciduous forest, extinct species of modern north temperate genera, well known from contemporaneous deposits in north Europe. Evidently, differential relief in those times was appreciably less than that of the present and it seems probable that much of what is now the western half of the British Isles was then a wide, forested extension of a previous North European Plain, which varied in altitude by no more than a few decametres.

Chattian and Miocene elements in the modern landscape of western Britain and Ireland

The Brassington Formation of the Pennines is the most extensive onshore Miocene succession in the UK It is preserved as outliers in Lower Carboniferous Limestone During the Cenozoic, central England underwent uplift, with erosion of post-Mississippian strata from the Pennine axis in the Peak District The Brassington Formation is hence significant in reconstructing Cenozoic geological history It is non-marine, derived from Triassic sandstone and of Mid–Late Miocene age The c 60 outliers occur in three clusters over c 220 km2 They are remnants of a sedimentary prism at least 75 m thick and with a volume of c 10 km3 Suffosion of bedrock, conditioned by aggressive precursor fluids of hypogenic origin, was the major control on subsidence The calculated volume of the fills in the Bees Nest and Green Clay outliers is 37–50 × 106 m3 Referenced to a sub-Miocene surface at c 450 m OD in pre-subsidence times, the original volume of this subsidence complex was c 218 × 106 m3 and the aggregated volume of the Late Neogene White Peak palaeokarst was at least 066 km3 Subsidence was concomitant with Pliocene uplift of the Pennine Axis, suggesting suffosion accommodation of 3 × 106 m3 per km2 or 244 m3 per annum

Peter Walsh

Papers

The preservation of the Neogene Brassington Formation of the southern Pennines and its bearing on the evolution of Upland Britain

A dissolution pipe palaeokarst of mid-Pleistocene age preserved in Miocene limestones near Staszów, Poland

Chattian and Miocene elements in the modern landscape of western Britain and Ireland

A reassessment of the Brassington Formation (Miocene) of Derbyshire, UK and a review of related hypogene karst suffosion processes