Summary During the last few years, a geologically little known area of south-east Durham, lying between the worked area of the Durham coalfield and the West Hartlepool Fault, has been explored by a gravity survey and a series of boreholes, with a view to the possible siting of a new coal mine. This work has proved an extension of the Durham coalfield, lying in a downfolded area beneath Permian rocks and fairly thick glacial deposits in the neighbourhood of Dalton Piercy. Some thirty million tons of coal are probably present in seams in the communis Zone of the Durham Coal Measures, but these are unlikely to be economically workable at the present time. The six new bore-holes have been correlated with earlier boreholes in the Fishburn area to the west and with shafts and boreholes, including two of the recent offshore bore-holes, to the north and east. Additional data obtained from the cores of the Permian rocks have augmented earlier work and led to a clearer understanding of some outstanding problems, in particular the position within the sequence of the thick Hartlepool Anhydrite and its probable relationship to the Middle Magnesian Limestone reef of Durham. Two alternative interpretations of the structure are offered in the paper; one assumes the likely easterly continuation of the Butterknowle disturbance, and the other the termination of this fault by an extension of the north-south trending Castle Eden disturbance.
The cast of a Coal Measures tree seen in position of growth is described. The cast is about 13 feet long, and evidence is given that the original tree trunk was probably at least 38 feet long before it became completely buried in sediment. The precise history of the tree is unknown but the rate of sedimentation round about it must have been very high.
A deep borehole has recently been drilled in search of oil and natural gas near Croxteth Park, Liverpool. The borehole penetrated Recent and Glacial deposits and a minimum of 1,306 ft. of Permo‐Triassic sandstones before crossing the large Croxteth Fault and entering rocks of the Millstone Grit Series. Thereafter, a sequence of strata extending from almost the top of the Millstone Grit down to beds in the upper part of the Carboniferous Limestone Series has been proved for the first time in the area. The limestones have yielded a large fauna.
SUMMARY New evidence on the sequence of Permian beds off Northumberland and Durham from boreholes drilled between 1974 and 1976 is reported, and it is considered along with data obtained from earlier offshore bores. The bores confirm a rapid thinning and disappearance of the Hartlepool Anhydrite westwards towards the present coastline, a thinning northwards from an area of maximum accumulation lying towards the southeast, and lateral passage into bedded dolomites. This thinning is regarded as depositional rather than the result of solution at a much later date, although penecontemporaneous deposition and re-solution might account for some intra-formational collapse structures present onshore. No clear evidence has been found to support the former extension shorewards of significant thicknesses of bedded anhydrite corresponding to the so-called Hartlepool Anhydrite or Seaham residues, although these could have originated from resolution of deposits formed in ‘isolated’ evaporite pans. In the light of the new data and subsequent re-examination of the cores from the Seaham Bore, some re-interpretation of the stratigraphy is proposed in which the Hartlepool Anhydrite is regarded as equivalent in age at least to the upper part of the reef, and possibly even to the whole, while the Seaham Beds revert to being part of the classic Concretionary Limestone. No correlation with either Yorkshire or the Zechstein basinal deposits is proposed in view of the uncertain value of Calcinema permiana (King), and further information is required.
Recent bores indicate that the basal Permian (Yellow) Sands of N Durham were deposited largely sub-aerially as dunes 50 m or more high on an almost planar Coal Measures surface. Many of these were inundated by a placid sea and covered by the Marl Slate and Passage Beds. Continued subsidence allowed the succeeding lower Magnesian Limestone to accumulate more rapidly on the slopes of thinly covered dunes possibly with relative relief of 30 m and minor slumping occurred over wide areas. Uplift and tilting led to deepening of the basin to the east and partial erosion of the lower Magnesian Limestone and Marl Slate on land followed by reef development. Anhydrite deposits formed contemporaneously or rather later than the reef. Inshore in N Durham these crystallized discretely from sulphate-rich dolomite muds possibly partly in a sabhka environment with ratio of evaporite to dolomite increasing eastwards towards the basin, ultimately to form continuous, bedded deposits some distance from the present shoreline in N Durham but on shore near Hartlepool. Breccias formed contemporaneously with the evaporites partly due to crystallization pressure and later removal of sulphate.
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