The tufa that forms the subject of these notes occurs on the eastern side of Park Brook in Upper Old Park Wood, 2 miles north-west of Lydney (6 in. O.S. Sheet, 47 N.W. Glos.).

The rarity of drifts in the Crouch Valley has been often remarked. The only river gravel marked in it on the Geological Survey Map, sheet I N.E., is a small patch at Little Hayes, a couple of hundred yards north of the Crouch, and 1¼ miles S.S.W. from Woodham Ferrers railway station. In the Evolution of the Essex Rivers (1922, p. 47), an analysis of the five chief constituents, based on a collection made by Mr. H. J. Nicholson, recorded some Jurassic sandstones which I regarded as probably derived from the boulder clay on hills about three miles north and north-west. A visit to the pit last year in order to obtain larger specimens of the Jurassic material yielded various cherts; one is a typical Rhaxella chert, which has not been previously recorded so far to the south-east. A thin bedded oolitic chert, which was different to any that I knew, was submitted to Mr. H. C. Sargent with the inquiry whether it might be one of the Carboniferous cherts of the Midlands. Mr. Sargent identified some of the inclusions as silicified oolitic grains, and rejected the rock as Midland Carboniferous. The specimens and slides were also kindly examined by Professor Boswell, who showed them to Mr. E. T. Dumble for comparison with the Rhaxella chert found by him in the Crag; they also did not know any similar rock. The specimens were then sent to Dr. Morley Davies, who confirmed the identity of the one specimen with the ordinary Oxford-Buckingham Rhaxella chert, and has, in the previous note, described the other as a Rhaxella chert in which the spicules are the nuclei of oolitic grains.

Travellers in Persia rarely diverge far from the beaten track between town and town, and there are areas in the South Persian mountains, hundreds of square miles in extent, in which there is no record of penetration by Europeans. Needless to say, such unexplored regions are frequently treasure houses of geological interest of sometimes the rarest and least expected kind.

The subject matter of the present note is furnished by the abnormal redness of many parts of the Arran Carboniferous. W. Gunn, in his invaluable memoir, records this colouration without particular comment; but, as Scottish geologists are aware, B. N. Peach, under whose supervision Gunn carried out his survey, has long claimed that the Arran Carboniferous is stained by solutions that have percolated down from overlying New Red Sandstone. After a careful consideration of the exposures, I feel convinced that two features of Peach's proposition are secure:—

(1) The red colour of much of the Arran Carboniferous is not original.

(2) It must be in some way connected with the New Red Sandstone.

The following remarks have been suggested by the perusal of Mr. E. B. Bailey's draft of his paper on the “Subterranean Penetration by a Desert Climate”.

The fossils to be described were collected by Messrs. C. Barrington Brown and R. A. Baldry, to whom I am indebted both for the opportunity of examining these forms and for the details given below of their horizon and locality, for which they are entirely responsible. The collection has been presented by them to the Sedgwick Museum, Cambridge.