Every one who has traversed our Chalk Downs must have noticed here and there shapeless masses of grey stones, half buried in the turf. Sometimes they are found in groups, like the shattered ruins of some ancient temple, and at other times they occur in isolated blocks, as though giant hands had hurled them at random over the hills in wanton sport. At one place, near the village of Kennet, they assume the appearance of a multitudinous flock of sheep, and are known by the appropriate designation of “Grey Wethers,” whilst at other places in the same vicinity they bristle on the hill-sides, and trail along the valleys like the débris of an avalanche or the moraine of a glacier. Nowhere do they exist in such profusion as on the west of Marlborough, but they are found scattered over the whole Chalk area of this district. At the western end of it they consist chiefly of saccharoid sandstone. Further east, especially around Newbury, they become smaller, harder, and more crystalline; whilst in the neighbourhood of Great Bedwyn, and occasionally elsewhere, they take the form of pudding-stone, being agglomerations of flint pebbles, cemented together in a matrix of siliceous sand.

Basalt groundmass textural nomenclature is reviewed and revised. The intergranular and ophitic extures are seen as end members of a series with steadily increasing grain-size, the international representative of which is here termed the “isogranular” texture. Undere intrusive conditions the series may be extended to include the poikilitic texture. Ophitic texture is regarded as an intergrowth;the term “sub-ophitic”s not suitable for basalts but may be retained for texturally isotropic rocks. When basalts cool hurriedly they will tend to develop an intergranular texture whereas extension of the crystallization period permits the formation of an ophitic texture. Cooling conditions will be determined by a combination of the effects of the volatile concentration and the flow characteristics, the latter partly depending on topography.

The Themed Fault marks the southernmost border of the Early Mesozoic passive continental margin of north Sinai. This 200-km long fault transects the northern part of the Tih Plateau that supposedly occupies a tectonically stable area. Post-Middle Eocene–pre-Early Miocene rejuvenation of this fault proceeded by right-lateral wrenching and represents a newly recognized phase of deformation in the history of north and central Sinai. The minimum estimate for the strike-slip movement on this fault is about 300–750 m. To the north of the Themed Fault is a narrow fault belt (Sinai hinge belt) that marks the boundary between a tectonically unstable crustal block to the north (the north Sinai fold belt area) and a tectonically stable crustal block to the south, the main part of the Tih plateau area.

Four phases of dextral wrenching rejuvenated the faults of the Early Mesozoic passive continental margin in northern Egypt; one of them affected the Themed Fault. The oldest (Dl) deformation is early Late Senonian and is related to the closure of Neotethys and the Eastern Mediterranean basin. The D1 deformation proceeded by pure wrenching in the north Western Desert of Egypt. In contrast, it proceeded by transpression in north Sinai due to the irregular plate boundary and the relationship of this boundary to the slip vectors. D2 deformation (post-Middle Eocene–pre-Early Miocene) is clear in the Themed Fault area although reported herein for the first time; it is related to continued closure of the Eastern Mediterranean basin and proceeded by pure wrenching. D3 deformation (Late Oligocene–Early Miocene) proceeded by divergent wrenching in the north Eastern Desert and is kinematically related to the transfer of slip from the nearby faults of the Suez rift. D4 deformation (post-Early Miocene to Recent) affected the Sinai hinge belt by pure wrenching and is probably related to the left-lateral slip on the Dead Sea Transform and the related drag of the eastern edges of the fault blocks of this hinge belt. Recent seismic activity in the Sinai hinge belt perhaps indicates that the D4 deformation has continued to the present time, although morphological expression of recent tectonic movement is lacking. In contrast, the Themed Fault is seismically quiet at present.

The evolution of Neogene volcanic activity in the Central Taurus is investigated; stratigraphical and radiometric age data from the Ürgüp (Kayseri) basin idicate that volcanism in the area began at least as early as Upper Miocene, lasting up to prehistoric times. The volcanism maintained throughout this time interval a calcalkaline character. The diachronous end of calcalkaline volcanism along the Taurus margin is tentatively related to the differential collision between the Afro-Arabian and the Anatolian plates, probably due to an original irregular shape of the Anatolian continental margin.