Notices of Memoirs — Brief Abstracts. 179 



■whilst in others the mesial furrow varies very much in depth, being 

 almost obliterated in some. 



Greenfell, J. Gr. Lower Limestone Shales, Clifton. Trans. Clifton, 

 Coll. Sci. Soc, part iv. pp. 17-23. 



These beds, consisting of alternations of shale and thin limestones, 

 separate the Old Eed Sandstone from the Carboniferous Limestone, 

 the thickness of the last being 1450 feet, and that of the shales 500. 

 The " bone -bed," over 100 feet up in the shales, was once taken to 

 be their base. 



The new railway gives a good section, a detailed account of which 

 (showing 148 beds, with a thickness of over 130 feet) is given, and 

 the result of the examination is to throw the " passage-beds " of Mr. 

 Sanders into the Carboniferous series, and to draw the line sharper 

 between that and the Old Red Sandstone — Carboniferous fossils 

 having been found to a lower depth than before. 



The bearing that this may have on the " Devonian question " is 

 noticed, and a conglomerate-bed is taken as the top of the Old Red 

 Sandstone, which, however, may run a few feet higher. The beds 

 seem to thin out rapidly along the strike (S.W.). 



Gkeenfell, J. G. Iron Mine recently opened in the Royal York Crescent, 

 Cifton. Trans. Clifton Coll. Sci. Soc, part iv. pp. 46-53. 



The mine is sunk in Millstone Grit, the upturned beds of which 

 are overlaid by horizontal beds, probably Triassic, five to twelve 

 feet thick, and composed of clay with fragments and masses of 

 hgematite. At another pit, close by, these latter beds have not been 

 bottomed at a depth of fifty feet, and a mass of hasmatite (probably 

 lenticular), ten to twelve feet thick, is worked in them : they are the 

 debris of the Millstone Grit beds. In the mine (an open pit) there 

 are two beds of hgematite, each four feet thick, with five of sandstone 

 and one of shale (also rich in iron). 



Most of the ore is Limonite, in six varieties ; red heematite occurs 

 in the inside of lumps of ore, and goethite in crystals coating the 

 limonite, and in cavities of the hajmatite. Quartz and sulphate of 

 baryta are associated with the iron-ore, the former disseminated 

 through the haematite, and in crystals ; as a rule, the silica has been 

 deposited after the iron ; the sulphate of baryta is in the form of 

 small thin tables in cavities in the ore and in the sandstone-matrix. 



The ore was introduced since the deposit of the beds, and the 

 author thinks that the cavities in which it is found may have been 

 formed by the dissolving away of limestone that once existed amongst 

 the sandstone beds. 



From the perpendicularity of the stalactitic masses of limonite, 

 it is clear that the deposit of ore must have taken place after the 

 beds were tilted into their present position. If, then, the overlying 

 horizontal beds are Triassic, and the lumps of haematite in them 

 were derived from the Millstone Grit, we can fix the date of intro- 

 duction of the ore, viz. during the Permian and Bunter periods. 

 The author thinks that the iron may have been derived from the 

 carbonate of iron of the Coal-measures that have been denuded away 

 in the neighbourhood . 



