SURFACE SLIPS 41 



lines, by the dry overlapping of turf over turf, by surface wrinklings, 

 by bursting of gate fastenings. Even, however, when thus started on 

 its downward path, the progress of a landcreep is by no means always 

 sustained. Sometimes for years the gaping rents remain unwidened, 

 sometimes they fill with dust and debris. They play, nevertheless, 

 an important part in the promotion of the earth avalanches already 

 described. Water lodging in them penetrates to the marl, greases the 

 base on which the upper soils rest, and expedites the slip. 



I believe that even during my brief span on Tutira scarcely a rood 

 of marl in the eastern run has not been affected in some degree by the 

 great rainfall has not slid seaward, perhaps a few inches, perhaps a 

 few feet. 



Landslips and landcreeps may, in fact, be considered comple- 

 mentary to the earlier processes of subcutaneous erosion. In the valley 

 of " Newton " paddock we have an example of surface wear and tear 

 arrested from lack of sufficient fall. There the local stream, blocked 

 and barred with limestone debris, still runs several hundred feet above 

 sea-level. The original upper soils too, torn and patchy, have not yet 

 been completely sloughed. 



In the valley of the Maungahinahina, however, where the fall nearly 

 reaches sea-level, and where, moreover, the mouth of the great gap abuts 

 directly on to the Waikoau river, we get an almost perfectly completed 

 bit of water sculpture five or six hundred feet deep and nearly half a 

 mile in width. The fibrous, rooty humus, the pumice grit, the red 

 sands, the clays are gone, the great scoop they used to hide is wholly 

 revealed. Percolation and soakage has developed into the under- 

 runner system, that into the open gulch, the gulch into multitudinous 

 lateral gorges, until the loose heterogeneous mixture of soils that once 

 filled the huge interstice to the brim has been scoured out and the 

 marl basis of the gap exposed. Lastly, unable to cope with and carry 

 off the vast quantity of limestone fragments, portions of the original 

 rock-cap slid into it from either side, the little stream has finally left 

 them piled and prominent in a sort of moraine at the mouth of the gap. 



Nevertheless, although thus buffeted by deluges and sapped by 

 earthslips, the remaining portion of the rock-cap of eastern Tutira is 

 likely to endure for an almost incalculable period. Attrition is enor- 

 mously slow. 



During my ownership three only of the great grey squares into which 



