470 Notices of Memoirs — Prof. Lapivorth's Address. 



this Band, that being the usual colouring-matter of cretaceous green 

 sands. A darker tint of green pervades the middle portion of the 

 bed, giving it the appearance of being ' hearted,' as the expression 

 goes. Eather over a mile from this place, Mr. Whitaker observed 

 in the tower of Husborne Crawley Church a quantity of green sand- 

 stone of a bright colour, and sometimes of a glassy texture, which 

 has been recognized as like some that occurs in the Lower Greensand 

 of Ightham, Kent. It is a serviceable-looking stone, and the bright- 

 ness of its colour adds beauty to the brown sandstone, of which the 

 edifice is mainly built. The stone seems to be a counterpart of the 

 green sand in the Apsley Section, and similarly colour-bearted. 

 Professor Bonney, on receiving specimens of the Husborne Crawley 

 rock, but speaking from sight only, doubts, however, whether it is 

 the same as the green sand at Apsley. It may be mentioned that 

 l^ieces of the same rock have been dug up in the roadway half a 

 mile from the church, and a larger boulder-like piece lies by the 

 roadside, on the outskirts of the village green. Adjoining the church- 

 yard is a very old-looking excavation, that suggests the spot at 

 which this stone may have been got. Seeing the difficulty of trans- 

 porting stones in olden times, it is extremely unlikely that the stone 

 came from a distance. Possibly, therefore, there may be some local 

 equivalent of the Lower Greensand of Kent in the Bedfordshire 

 Greensand, which, if not entirely dug away in supplj'ing the stone 

 for Crawley Church, may yet again be brought to light. 



VIII. — British Association for the Advancement of Science, 

 Edinburgh, 1892. 



Address to the Geological Section by Professor C. Lapworth, LL.D., 



F.K.S., F.G.S., President of the Section. 



(PART II,) 



In the stnicture of our modern mountain ranges we discover the most beautiful 

 illustrations of the bending and folding of the rocky formations of the earth-crust. 

 The early results of Rogers among the Alleghanies, and of Lory and Favre in the 

 Western Alps, have been greatly extended of late years by the discoveries of Heim 

 and Baltzer in the Central Alps, of Bertrand in Provence, of Margerie in Languedoc, 

 of Dutton and his colleagues in the western ranges of America, and of Peach and 

 Home and others in the older rocks of Britain. The light these researches 

 throw upon the phenomena of mountain structure will be found admirably 

 summarised and discussed in the works of Leconte, of Dana, of Daubree, of 

 Reade, of Heim, and finally in the magnificent work of Suess, the ' Antlitz der 

 Erde, ' of which only the first two volumes have yet appeared. 



Looking first at the mountain fold in its simplest form as that of a bent rock- 

 plate composed of many layers, which has been forced into two similar arc-like 

 forms, the convexities of which are turned, the one upwards and the other down- 

 wards, we find in the present mountain ranges of the globe every kind represented. 

 We commence with one in which the arch is represented merely by a gentle swell 

 in the rock sheet, and the trough by an answering shallow depression, the two 

 shading into each other in an area of contrary flexure. From this type we pass 

 insensibly to others in which we see that the sides of the common limb or septum 

 are practically perpendicular. From these we pass to folds in which the twisted 

 common limb or septum overhangs the vertical, and so on to that final extreme, 

 where the arch limb has been pushed completely over on to the trough limb, and 

 all three members, as in our note-book experiment, are practically welded into one 

 conformable solid mass. 



