428 Transactions. 



locality available at present, and they suggest that when other areas are 

 similarly plotted the minute structure of the area may be determined, and 

 some of its apparent irregularities may be removed. 



From this series of sections it will be seen that certain sands, sandy 

 clay, and clay beds are persistent and regular over a fairly wide area. Well- 

 marked beds of this type occur at a depth of between 40 ft. and 80 ft. below 

 the surface, another between 150 ft. and 175 ft., another between 350 ft. 

 and 400 ft. Similar, but less persistent, beds divide up some of the main 

 gravel-beds into subordinate and irregular layers. From the occurrence of 

 shells in certain of these beds it may be inferred that they are marine or 

 aestuarine, although it is possible that some are not. It will also be seen 

 that a bed of gravel, thick and continuous in one well, is frequently broken 

 up in a neighbouring v/ell by sand and clay beds. As nearly all these 

 gravel-beds will yield artesian water, it is obvious that it is almost impos- 

 sible to state the exact depth of the different water-bearing strata in any 

 locality, as a particular water-bearing bed of one well may be divided up 

 into a number of thinner beds in a neighbouring well, where, owing to dif- 

 ferent conditions of pressure, friction, and the supply of water, flows of 

 varying amount may be obtained from what are apparently different beds, 

 although they are really connected with one another. It is thus impossible 

 to predict with any degree of certainty the number of water-bearing beds 

 that will be encountered within a given depth, or that water will be met 

 with at any particular level, though certain belts are extremely likely to 

 contain it in one or more levels. It will be noticed that a very uniform and 

 widely distributed water-stratum is found about the 400 ft. depth ; all the 

 wells from this show a marked regularity in the height to which the water 

 rises above the surface. This is, in all probability, a stratum covered by 

 marine or aestuarine bed, an occurrence which suggests that the conditions 

 were uniform over a comparatively wide area. 



This series of sections shows the presence of peat-beds, sometimes singly, 

 and again divided by thin bands of clay and gravel. Remains of wood 

 are also encountered. 



The height to which the water rises in any particular well is also found 

 to depend principally on the depth, although there are one or two departures 

 from the rule, as mentioned in dealing with Series No. 1. 



Series No. 3. — Papanui, St. Albans, Richmond, and Shirley. 

 (Plate XI.) 

 This shows the structure and character of the water-bearing beds in the 

 district stretching from Fendalton, through St. Albans, towards the coast. 

 The first well lies on the edge of the artesian belt, and shows, at all events 

 in its upper levels, a marked predominance of gravel ; but on going east 

 the amount of gravel in the sections decreases, and finer detritus becomes 

 more important. There is a certain element of regularity in the arrange- 

 ment of the beds. A well-defined clay-bed extends almost all over the area, 

 with an occasional coating of peat, and under it is a fairly regular band 

 of gravel. Under this lies an extremely persistent bed of sand or sandy 

 clay, which contains at times marine shells, thus showing that the sea 

 stretched over the area at a comparatively recent date. This is succeeded 

 below by a somewhat broken set of beds composed of gravel separated by 

 peat and also by fine detrital matter ; but in spite of the apparent irregu- 

 larity there is an approach to order in the arrangement, and a more com- 

 plete set of sections would show this absolutely. Even the sections as they 



