Shirley and Horsfield (1940) in describing the Carboniferous Limestone of the Castleton-Bradwell area in North Derbyshire submitted evidence that the richly fossiliferous rocks of B2 age, the “Castleton reef knoll limestones lie with strong unconformity on the D1-D2 limestones, being piled against steep slopes or cliffs of Mid-Carboniferous age of at least 550 feet. The Nun Low limestones of P age follow with a similar relationship to the Castleton Limestones”.

Dehée (1929, p. 26) has pointed out that there has been much confusion and difficulty in distinguishing A. concentrica from A. (Cleiothyridina) roissyi, and Weller (1914, p. 473) referred to Davidson's too broad interpretation of that species. One impression [H. 251] from Poleshill which Whidborne figured (1897, pl. xviii, fig. 3) under the latter name does not possess the characteristic spinosity of A. (Cl.) roissyi, but agrees instead with A. concentrica which is a typical Devonian species characteristic of the Upper Devonian, as Dehée remarks who figures examples of it (1929, p. 26, pl. iv, figs. 4−6) from Etroeungt.

Many fossils in the older rocks have been distorted by pressure, and if only one specimen is available it is often difficult to be sure of its original proportions. Sometimes, however, there is a specimen which not only furnishes sufficient data for the determination of its original form, but can be made to yield a photograph in which the distortion is corrected. In his paper on “Slaty Cleavage” Harker1 showed how, in such cases, the distortion can be determined, and he referred to an earlier paper by Dufet2 in which the same principle is used, though in a different way. So far as I know the method of correcting the distortion photographically has not previously been employed.

When recently on military duty in India, the writer was in correspondence with Mr. D. N. Wadia on the known distribution of granite within the ranges of the Himalaya, arising out of a statement by Mr. Wadia in his General Presidential Address to the 29th India Science Congress, 1942, on “The Making of India”. Therein it was declared (p. 7): “In these earth plications masses of crystalline igneous rocks, granites, from the depths of the earth, have been pushed up through the sedimentary cover and now occupy the central zone of highest elevations. The sublime snow-capped peaks of the Himalaya from Mount Everest to Nanga Parbat, all are built of this axial granite core,” etc.

Attention has recently been directed, particularly by the writings of Boswell (1942) and Smithson (1941, 1942), to the instability of detrital minerals. In nearly all cases where etching of mineral grains has been described the rocks have been deposited under water, as members of a continuously sedimentary series.