686 KEPORT— 1887. 



magnitude, and a continent of corresponding- size, to give tlie necessary drainage 

 area — to wit, the continent of Archaia. 



To this northern and -western land may be traced the pehbles and groups of 

 pebbles found in the coal seams of Lancashire — such, for example, as the Trencher- 

 bone seam, uear Kearsley — and which have probably been brought do-wn in flood 

 time from the uplands. They are, v\'ith few exceptions — one a granite — quartzites, 

 and have been deri\ed from conglomerates formed by the break-up of the Cambrian 

 and Ordovicean rocks — most probably from the Old Red Sandstone Conglomerates 

 of Scotland, or of a continuation of Scotland in the direction of Norway. 



It only remains for me to add that in this paper I have entered upon the labours 

 of Phillips, Godwin-Ansten, Jukes, und Hull, and that 1 have dealt only in outline 

 with a difficult and complicated question. 



2. On the Structure of the Millstone Grit of the Pennine Chain. 

 By Professor W. Boyd Dawkins, F.B.S. 



In this communication attention was drawn to the normal constitution of the rock 

 and to the granular quartz and the orthoclase sometimes sufficiently fresh to show 

 the cleavage, which have evidentlj- been derived from the destruction of granite 

 rocks, and are not much rolled. The orthoclase has generally been reduced to 

 kaolin bv the passage of waters charged with carbonic acid, and sometimes is 

 wholly removed, the cavities being coated with a secondary deposit of quartz 

 crystals derived from the break-up of the orthoclase. The sand-grains also are 

 coated in the same way. It is <an ancient sandbank of a sea that beat upon rocks 

 composed of granite and crystalline schists and later rocks, as is proved by the 

 pebbles of vein quartz and the rolled garnets of the rocks which formed at this 

 time the massif of Archaia. 



3. On Foreign Boulders in Coal Seams. By Make Stirrui', F.G.S. 



Among many interesting problems connected with the Carboniferous rocks still 

 awaitino- solution, not the least interesting one is that of the mode of occurrence 

 and the source of the foreign boulders which are occasionally found in our coal 

 seams. 



The importance that attaches to these boulders is that, could we read their 

 history aright and ascertain whence they came, it would give us some clue to the 

 physical features of the old land areas in pre-Carboniferous times, and enable the 

 palffiophysiographer to construct his charts with a greater probability of correct- 

 ness than at present. Furthermore, could the means by which these boulders were 

 deposited in the coal be clearly pointed out, they would either confirm or refute 

 the aro-uments of those physicists who contend that this earth of ours has experi- 

 enced oreat periodic alternations of climate, cycles of cold and heat, due to cosmic 

 causes acting through all time. 



The presence of these foreign boulders in coal seams has been long known, but 

 they have always been considered rare and phenomenal. The late Mr. E. W. 

 Binney in 1851 read a paper on the subject before the Manchester Literary and 

 Philosophical Society (vol. ix. second series, p. 306), in which he describes and 

 fio-ures some rounded grey quartzose stones from the 4-feet mine at Patricroft 

 and from another seam under the same mine at Pendleton. 



Other notices may be found in the ' Transactions of the Manchester Geological 

 Society ' by Mr. John Plant, the late Mr. J. Aitken, and others. 



These boulders are, as a rule, hard siliceous grits or quartzites, ranging in colour 

 from pale to dark grey, and would betoken by their character and mineralogical 

 composition that they were all derived from one common source. 



Though varying often in form and size they have this common characteristic — 

 that they are smoothed, often polished, with corners rounded oft' by abrasion. 



Their forms are various — roughly quadrangular, irregularly ovoid or elliptical, 

 occasionally globular, and all have evidently been water-worn before being de- 

 posited in the coal strata. A thin film of coal or shale, according to the matrix, is 



