THE GEOLOGY OF THE ENGLISH CHANNEL. 121 



which the Association enjoys advantages it greatly, but our debt to the 

 earlier workers remains undiminished, and in many instances they have 

 preserved evidence of great importance, whicli must otherwise have 

 been lost. 



PETROLOGY. 



To avoid the confusion which might arise from the system of 

 numbering the dredgings, whereby three distinct sets of samples have 

 all been numbered from 1 onward, the following method has been 

 adopted. Actual hand specimens from Dr. Allen's first dredgings are 

 referred to by the reference which the slides bear in the writer's 

 collection, similarly specimens from the second set of dredgings further 

 inshore, this will always be found to be a double number, such as 

 " 356/1 ", with sometimes a letter added also. In those cases where 

 sands only have been examined, all of which occur in Dr. Allen's 

 dredgings alone, the station number already published in the Journal is 

 used, prefixed by the letter "A." The most recent stations, of last 

 year's work, have the letter " M " set before the number ; and Mr. 

 Hunt's own figures are used with the letter " H " prefixed. Mr. E. N. 

 Worth's specimens bear a number prefixed to which is the letter " W." 



Where more than one rock is described from a station small letters 

 are added after the number, by which the various specimens are 

 discriminated. 



With reference to the dredgings taken last year, the rule has been 

 adopted that if several varieties or specimens of one class rock have to 

 be described, those are set first which are nearest the Eddystone, and 

 of those at equal distance precedence is given to the more western. 



Throughout, the abbreviation " Edd." represents the word Eddystone. 



GRANITES AND ALLIED ROCKS. 



A large number of specimens, generally distributed over the area 

 examined, fall within the popular acceptation of the term ' G-ranite' 

 but the greater part of these when submitted to microscopic examina- 

 tion must be transferred to the Quartz-diorites in consequence of the 

 distinct preponderance of plagioclase felspars. Since it is impossible 

 to be certain in which class to place many of the specimens on mere 

 inspection, and it has been out of the question to section all, those as 

 to which any doubt exists are hereafter collected under the head of 

 ' Granitoid Rocks.' 



GRANITES. 



Boulder. S.S.W. Start, 15 miles. Weight about 8 cwt. 



A fine-grained white granite, with very uniformly disseminated 

 black mica. The little felspars are bright and fresh, and the simple 



