5© BROWNRIDGE : BOULDERS IN THE COAL MEASURES. 



*No. I Specimen. —The grains in the rock are remarkably v/ell 

 rounded. The majority are quartz, but there are some grains, also 

 rounded for the most part, which are brown in colour, more or less 

 opaque. I think it possible that these are decomposed felspar, stained 

 by infiltrated bituminous material. The quartz grains are cemented 

 by secondary quartz, sometimes, but not always, in optical continuity 

 with the adjacent grains ; cavities appear to be frequent in most 

 grains, but are generally of very small size; sometimes a tiny bubble 

 may be noted, but I think that they are commonly empty ; some 

 grains contain a number of small almost colourless belonites, rather 

 like silhmanite, which are commonly seen in the quartz of certain 

 old granitoid rocks ; others contain a flake of brown mica, a tiny 

 crystal or two, probably an iron oxide or a crystallite, which may 

 be zircon. I expect the quartz has been derived from an old 

 granitoid rock. The well-rounded grains difference this specimen 

 from those quartzites or grits which I have hitherto seen from 

 boulders in coal, but a specimen which I obtained from one of 

 the old quartzites of the Lickey Hills also contains many well- 

 rounded grains, and so does a quartzite in the Charnwood series ; 

 of course, I do not mean to suggest that we must look in this 

 direction for the parent rock. 



' No. 2 Specimen. — This rock differs but little from the last. 

 The grains, as a rule, I think, are not quite so well rounded, and 

 rather more are stained ; those containing the belonites are perhaps 

 not quite so common. A small grain may be brown tourmaline, and 

 T think this mineral is also included in a quartz grain. It is very 

 probable that this boulder comes from the same parent rock as the 

 other one.' 



Prof. Bonney, in his presidential address to Section C of the 

 British Association at Birmingham in 1886, described several 

 boulders found in coal, the examination of which he rightly considers 

 to be of great value, from the light it may throw upon the physical 

 conditions existing in the carboniferous period, and this opinion, 

 coming from a scientist of such great authority and experience, 

 should expand this field of inquiry, and in time lead to practical and 

 valuable results. 



The reason why these stones are thus found located in such 

 phenomenal positions can only at present be surmised, as the subject 

 is at present rather vague ; but the theory has been adduced that 

 they have been carried down by masses of floating vegetation in a 

 manner similar to that recorded by travellers on the Amazon, where 

 in the swamps and shallows such masses are seen floating, carrying 

 foreign matter along with them. It has also been suggested that 



Naturalist, 



