656 HEPOET — 1888. 



of Science ' for September. Further investigations will be published in succeeding 

 numbers of this journal. The Oligoclase presents an appearance like that seen in 

 devitrified glass, where numbers of small star-like masses appear in the transparent 

 matrix. The quartz, which unfortunately has been superficially polished, exhibits 

 twin structure when viewed along the axis oo P, the alternate parts of the twin 

 being differentiated by smoky and clear quartz. 



In the interior a singular segregation of foreign matter has taken place along 

 the plains of twinnir.'g, but in such a manner as to mark the outline of a hexao-ona'l 

 or ditrigonal pyramid. ° 



FRIDAY, SEPTEMBER 7. 

 The following Report and Papers were read : — 



1. Sixteenth Report on the Erratic BlocJcs of England, Wales, and Ireland. 



See Reports, p. 101. 



2. On a High Level Boulder-clay in the Midlands. 

 By Dr. H. W. Ckossket, F.0.8. 



3. On the Extension of the Bath Oolite under London, as shown hy a Beep 

 Boring at Streatham. By W. Whitaker, B.A., F.B.S. 



The attempts to get water from beds deep underground in and near London 

 have done much to reveal the geological structure of that district, and to prove what 

 was before only the theory of the geologist to be a fact, namely, that along part of 

 the valley of the Thames the regular succession of the formations is broken by the 

 'jccurrence of a mass of older rocks, rising up so as, in some cases, to come next 

 beneath the Gault. 



This has been brought about by the underground extension eastward of the 

 great line of disturbance, of which so much is seen at the surface in the west of 

 England, in the great saddleback of the Mendips, in the trough of the South 

 Wales Coal-field, and in the bringing in of coal-fields under Jurassic formations. 



Whether the Bath waters have anything to do with this disturbance I cannot 

 say, but we have not yet succeeded in tapping them under Loudon. 



Not the least interesting result of the set of experiments in deep boring has 

 been the discovery of beds of Jurassic age in two of the borings, at Meuxi's Brewery 

 and at Puchmond. These beds, though comparatively thin, can be referred with 

 safety to the lower division of the series, or that which is so well developed round 

 iiath, both from their character and from their fossils. 



A boring now being made by the Southwark and Vauxhall Water Company 

 at Streatbam, a southern part of London, has passed through the following for- 

 mations, and then, at the depth of 1,081^ feet, has passed at once into Jurassic 

 limestone : — 



feet 

 Tertiary beds .......... 241^ 



Chalk C23 



Upper Greensand 29 



CJault 188 



This limestone is hard, compact, for the most part of coarsely oolitic structure 

 and with small fragments of shells. It is almost exactly like some of the Forest 

 Marble of Wiltshire, so much indeed tliat specimens from the two can hardly be 

 distinguished. 



As it is in the two other borings nearest to Streatham that Jurassic rocks, also 

 referred to the Forest Marble, have been found, we may fairly infer the existence of 



