74 REPORT — 1870. 



On the Green Slates and Porphyries of the Lake-district. 

 By Prof. Haekness, F.B.S., and BE. A. Nicholson, D.Sc, F.G.S. 



The authors described the sequence of the rocks which in the Lake-country are 

 known as green slates and porphjTies, as being made up of traps at the base, of a 

 middle series consisting of ashes, traps, amygdaloids, and trappean breccias, and 

 of an upper series consisting of horustone porphyry. 



The former is very persistent over the Lake-district, while the latter is by no 

 means so uniform in its occurrence. The middle series varies much in mineral 

 character according to locality. The neighbourhood of Keswick and in Borrowdale 

 exhibits this series in its most typical form. West and north-west from Keswick 

 the ash-beds are less abundant, their place being occupied by a porphyry with 

 large crystals of felspar ; and in the northern slopes of the CulcleckfeUs this por- 

 phyry' is the sole representative of the middle portion of the group. At Carrickfell 

 this porphyry is in contact with syenite ; and here its character has become greatly 

 modified, it appearing as a diorite: and at Roughtengill it has also undergone 

 changes from the influence of granite veins ; for here it occurs as a hypersthene 

 rock. 



The green slates and porphyries of the Lake-country represent the Upper 

 Llandeilo and a portion of the Caradoc rocks ; and their average thickness does 

 not seem to be more than 5000 feet. 



On Some Thermal Spritigs in the Fens of Cambridgeshire. 

 By F. W. Harmer, F.G.S. 



■ In several farm-yard wells near Chatteris in Cambridgeshire, of the depth of 

 from 10 to 14 feet, the author had found on the 14th of jNIarch, 1870, water of the 

 temperature of from 66|° to 742° Fahr., that of the air being then but 37° in the 

 shade, and the water in Vermuden's drain (one of the main arteries of the fen- 

 drainage, which is within 100 yards of one of the wells) having at the same time 

 but 39 of heat, and being covered with thin ice. 



At a subsequent visit to one of the localities on June 2nd, the temperature of 

 the air being in the shade 70°, and of the water in the neighbouring (kains 711° 

 the well showed 791° of heat. 



An analysis of the water had been made by Mr. Francis Sutton, F.C.S., of 

 Norwich, but he had been unable to discover any reason for supposing that the heat 

 was generated locally by chemical causes. 



The fen-district being below the sea-level, the ground is permanently saturated 

 with water at a short distance from the surface, and as this water at the slight depth 

 of 10 feet seems constantly to maintain, summer and winter, such an abnormal 

 temperature, its agricultural eifects cannot be inconsiderable. 



The author hoped that an endeavour would be made by local geologists to ascer- 

 tain whether these thermal springs extended beyond the area of about 10 to 15 

 square miles in which he had observed them, and also to detennine in what way 

 and by how much the agricidture of the district was affected by them. 



Mr. Judd, F.G.S., of the Ordnance Survey, had informed the author that the 

 secondary strata which underlie the alluvial deposits of the feus are in the adjoin- 

 ing counties considerably faulted and dislocated ; but whether in this way the 

 water described may be in commimication with the central heat of the earth, or 

 whether the matter is to be explained by chemical causes, he does not at present 

 • offer a decided opinion. 



On the Extension of the Coal-fields beneath the yieiuer Formations of England, 

 .and the successive Stratir/raphical Changes to which the Carboniferous Rochs 

 have been subjected. By Prof. Edward Hull, M.A., F.R.S., F.G.S. 



The author commenced by referring to the paper which Sir R. I. Murchison had 

 laid before the British Association at Nottingham, " On the Parts of England and 

 Wales in which Coal may, or may not, be looked for," and expressed his gi-atifi- 

 cation that his own views, arrived at by a somewhat different process of reasoning, 

 coincided in the main with those of his respected chief. Especially was this the 



