A sedimentary study of the Fell Sandstones of the Coquet Valley, Northumberland

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Abstract
Summary: The Fell sandstones are about 1000 feet thick in the Coquet valley. They form the upper part of the Tuedian, which is the lower division of the Lower Carboniferous in Northumberland. Current-bedding is generally present, and occasionally shows deformation structures. Directions of current-bedding indicate a source lying to the north-east. The heavy mineral content of the underlying Cementstone Group is distinct from that of the Fell Sandstones. The lower part of the latter, described as the mixed zone, contains a mineral assemblage common to both groups. The results of mechanical analysis show a marked degree of uniformity of grade-size throughout the Fell Sandstones. Coarser beds occur only very occasionally. Careful sampling from individual units of current-bedding indicates that all parts of a single unit generally yield almost coincident cumulative curves. Adjacent units of current-bedding often differ from one another in grade-size, evidently in response to the varying strengths of tho depositing currents. To the same cause may be ascribed the variations in the percentages of heavy minerals in samples taken from adjacent current-bedded units.