364 GEOLOGICAL WORK. [l892. 



specimens whose history absolves them from the slightest con- 

 nection with the family of " Flint Jack " show marvellously little 

 change, whereas others from the same beds are nearly converted 

 into pebbles by water and wear. We evidently as yet know 

 but little as to the precise action of water percolating through 

 beds of Gravel, either as to staining or whitening. . . . 



I hope next week to do some work at a patch of Gravel on 

 one of your highest points, five miles to the N. of this. With 

 very kind regards, yours very truly, H. P. BLACKMORE. 



J. Prestwich to Sir A. Gfeikie. DARENT-HULME, 15th May 1892. 



MY DEAR GEIKIE, Many thanks for your letter, and I trust 

 you will not find too much to quarrel with in my paper. I am 

 now continuing the same line of research over France and the 

 south of Europe. I shall there, however, be dependent on the 

 works of others (with the exception of France), whereas in Eng- 

 land I am acquainted with the whole of the ground. This is 

 of course a great disadvantage, which it is now too late to 

 remedy. 



You must have had a pleasant time in Paris, where formerly 

 I was well-known, but am glad to know that my old friends 

 Daubre'e and Gaudry are still to the fore. You do not tell me, 

 however, how you are. We should much like to know, if you 

 can find time to send me a few lines. I am thankful to say we 

 are both well. This quiet country life suits me physically and 

 mentally. . . . 



In reply to an inquiry from Mr Harrison we find him 

 writing at this time, " Decomposed flint pebbles are of 

 not unfrequent occurrence in various Tertiaries. They 

 lose their water of crystallisation, and some molecular 

 changes take place which render them white, soft, and 

 friable. These you have sent are from Lower Ter- 

 tiary (Woolwich and Reading ?) Beds. You speak also 

 of decomposed flints as well as pebbles. These are 

 unusual, but you send no specimen. . . ." 



