Canterbury and Westland. 391 



Tripp are still well preserved. The arrangement of the beds, owing 

 their deposition to glacier action can be well studied on the banks of 

 the lower Potts, a tributary of the Rangitata, crossing diagonally the 

 Lake Tripp valley, and of which section No. 11, plate 7, gives the 

 details. Several erratic blocks lie on the surface, below which bed 

 No. 1 appears. It is about 60 feet thick, and consists of morainic 

 accumulations, containing a large number of enormous angular blocks 

 of rock imbedded in yellowish silt. It is separated by a sharply 

 denned line from No. 2 grey moraine, also full of large angular blocks 

 in which the interstices are filled up by coarse greyish detritus, 

 thickness about 15 feet ; No. 3, yellow moraine, also replete with huge 

 blocks, of which, however, a number have rounded angles, thickness 

 about 90 feet ; No. 4, very hard fissile, yellow and white fine glacier 

 silt, having a horizontal position, some of the layers being as thin as a 

 sheet of paper. This bed has doubtless been deposited in a glacier 

 lake. It changes towards its upper portion gradually into sand and 

 fine gravel ; towards the bottom it is however sharply defined, thick- 

 ness about 40 feet. It reposes on No. 5 grey moraine, consisting of 

 a great number of mostly large and perfectly angular blocks, thick- 

 ness about 100 feet. Below this last deposit a bed of a thickness of 

 about 80 feet is visible, consisting of till, sand and silt, alternating 

 repeatedly with each other. The character of the beds for the lowest 

 100 feet could not be ascertained, as they are covered by a talus of 

 debris from the deposits above. It is thus clear that at different 

 times various conditions prevailed here. The upper deposits are 

 either lateral moraines of the Potts glacier branch once joining the 

 E-angitata glacier, or they belong to the latter when it divided here in 

 two branches, of which one travelled towards the Ashburton opening. 

 No. 3 was probably a ground moraine. The peculiar conditions of 

 this assembly of beds go far to prove that glaciers when advancing 

 again after their retreat, do not always clear out their former channels 

 of morainic deposits accumulated therein, and that even under favour- 

 able circumstances the finest glacier silt, when protected by moraines 

 of comparatively inconsiderable thickness, is so thoroughly protected 

 that no change in its stratification can take place. 



The Waimakariri Glacier. 

 This glacier in the height of the Great Glacier period obtained also 

 a considerable size. It was at least 54 miles long, reaching as 

 far as the middle portion of the Malvern Hills, where on the western 



