﻿232 DE. H. C. SORBY O:^ THE APPLICATIOIN^ OF [May I908, 



Plate XV. 



This shows ripples with not much drifting forward, rapid deposition, and 

 slight breaking-up of the fine-grained material, while still somewhat soft. 

 (Green slate, Langdale.) See p. 197. 



Plate XVI. 



In this is a thin layer of ripple-drift, over which is a fine-grained deposit, 

 very little broken up by the current bringing the coarser material, as if 

 partly consolidated. (Green slate, liangdale.) See p, 198. 



Plate XVII. 



Fig. 1. Oolite from Grantham, showing an amount of empty spaces nearly 

 equal to the theoretical minimum. (Magnified 50 diameters.) See 

 pp. 206-207. 

 2. Coralline Oolite from Scarborough, in which the interspaces, some filled 

 with calcite, are nearly of the same volume as when recently deposited 

 with little shaking. (Magnified 50 diameters.) See p. 209. 



Plate XVIII. 



Fig. 1. Wenlock Limestone from Easthope, showing angular fragments much 

 squeezed together. (Magnified 25 diameters.) See p. 209. 

 2. Carboniferous Limestone from Bristol : an unusual example of oolitic 

 grams conside)-ably influenced by pressure-solution. (Magnified 

 50 diameters.) See p. 226. 



Discussion". 



The Peesident observed that any paper coming from their veteran 

 comrade, Dr. Sorby, could not fail to be full of suggestion and to 

 be marked by that wealth of experimental detail and sagacious 

 calculation for which all his scientific writings had been dis- 

 tinguished. The present communication was the result of many 

 years of experiment and reflection, although the Author was now 

 confined to his room and unable longer to continue the prosecution 

 of active research. It was probably safe to say that, although only 

 his own brief summary of results had been read to the meeting, 

 the paper when published would be found to mark a new starting- 

 point for the investigation of the origin, history, and chronology of 

 rocks. An interesting point of connexion could be noticed between 

 the two papers communicated to the Society that evening. 

 Dr. V^^right, while lessening the length of the unit in the geological 

 time-scale, still dealt with a period of several thousand years. It 

 would be remembered that Earon Gerard de Geer, as the President 

 had recently announced, had discovered, among the marine deposits 

 that followed the retreat of the ice-sheet in Sweden, a remarkable 

 repetition of distinct layers which he interpreted as indicating the 

 succession of seasons in a series of years. And he was believed to 

 have lately detected among the deposits of the inland Glacial lakes 

 a similar series of apparently-seasonal deposits. But Dr. Sorby, 

 in the paper of which they had heard an abstract, thought himself 

 in a position to speak confidently of the number of minutes which 



