151 



would, during each succeeding spring, be more or less covered 

 with ice, and the slippery surface would facilitate the washing 

 down by the heavy rains of spring of the newly-formed detritus 

 of the previous winter. The deposit would generally be along 

 the line where the frozen snow ceased. This is not merely 

 conjecture, inasmuch as the writer noticed during the frost of 

 the winter of 1870, that a temporary thaw occurred, and the 

 valleys below a certain well-defined line were cleared of snow. 

 The frost again set in, and the snow which remained on the 

 hills and the upper part of the slopes was again frozen, and so 

 formed a snow-line along the side of the hills, very near the 

 level at which the Angular Gravel is most abundant. 



The age of this Gravel is, I think, nearly identical with that 

 of the river Gravel. The intercalation of the Deposits at 

 Longfords Lake shows that the Angular Gravel was being 

 deposited at the time when the stream was either depositing or 

 re-arranging the river Gravel, and before it had excavated the 

 bottom of the valley to its present depth. 



[Fig. 1. Section of G^-avel Pit at Longfords Lalce.1 



The intercalation of the Angular and River Gravel in this 

 section may be explained thus : — Angular Gravel was first 

 deposited at the foot of the hill. It rested against the slope of 

 the Inferior Oolite, and on the Eubbly Oolite (e.) This deposit 

 accumulated while that of the Eiver Gravel (d) was going on, 

 but probably, by reason of the wash of the stream, a slip took 

 place, and a mass of Angular Gravel (b) came down upon the 

 Eiver Gravel, and was spread over it by the stream, forming a 

 well-defined bed, thinning out on the side next the channel. 

 The deposition of Eiver Gravel continued (d), partially inter- 

 rupted by a second slip of Angular Gravel (b), but at length it 

 ceased, and the thin stratum of clay and dirt (c) was formed 

 upon it. After this the deposit of Angular Gravel (b) was 

 continuous for a considerable period; the bed being 8 feet thick. 

 This was succeeded by the coarse Angular Gravel (a). It is 



