distinctly present peculiarities. Sometimes long troughs of 

 slight inclination and of semi-circular transverse section 

 may be found. The peculiarity is observed that though 

 there is gravel, sand, and loam in them, shewing they once 

 contained bedded deposits, now the contents are somewhat 

 conformable to the outline of the section. I take it that 

 these have been restricted gullies between blocks of ice or 

 in frozen ground, which carried streams in summer and 

 which got choked in the normal way. When the choked 

 rivulet was overridden by ice, the overlying mass would 

 weigh down into the soft central part and the pressure 

 would become radial, squeezing down the upper middle 

 part, and squeezing up the lower deposit at the same time, 

 while arranging the pebbles in accordance with this 

 pressure, viz., placing their longest axes at right angles to 

 the resistance, which in a semi-circle would be vertical at 

 the sides, and approaching the horizontal towards the 

 bottom. This action would extend to the re-arrangement 

 of the pebbles in the parent rock if it were gravel (see 

 figure). As the gully at Erith [PL ii. fig. 2), extended 

 between two valleys, excavated since, and therefore later 

 in age, it does not belong to the latest fit of glaciation, but 

 is a good example, as it is covered by trail, &c. 



The effect of pressure on the pebbles and stones both in 

 the trail and underplight, is to place their flat surfaces 

 parallel with the surfaces forming the folds and festoons. 

 In my drawing I have not always been able to indicate 

 this, but it is to be understood as the regular appearance 

 in every case. 



It usually happens that the festooned layer or 

 underplight is so arranged as to present the folds 

 nearly upright, or so little inclined as to make the 

 nearly vettical position of the folds and their con- 

 stituent pebbles and fragments a conspicuous feature, 

 but occasionally examples may be found where the 

 inclination of the ground is such that the folds approach 

 the horizontal and frequently incline downwards, this is 



