Cbawford.- — On BidwiWs Front Hills. 417 



plains is not much above the sea-level, let us say 20 or 30 feet, while the 

 height of the ridge in question, I should estimate, in its highest part, to be 

 fully 300 feet above the sea. Now this is higher than the level of Greytown 

 or Carterton, and the corresponding level will probably be found in the 

 middle of the Taratahi Plain. 



At first sight there is nothing extraordinary in findmg a spur running 

 out from the mountains into a plain, but when we examine the structure of 

 this ridge we find much upon which to speculate. I am aware that there 

 are some remains of old rocks, apparently belonging to the Eimutaka 

 series, in the core of the ridge in question, -because years ago I found them 

 myself, but the mass of the range appears to be entirely composed of river- 

 borne gravels and clays (perhaps the latter would be better described as 

 muds). The cuttings for the formation of roads bring this point more 

 clearly to view than formerly. 



Now this ridge having been formed of river-borne gravels and clays, the 

 water at the time of its formation must have stood or run at a higher level 

 than it, the ridge, stands at present, and either great denudation of the 

 lower valley must since have taken place on both sides of the ridge, 

 or the slope of the ridge must show a tendency to a termination of 

 the deiDosit, either as a talus of materials dropped into a lake or as a finish- 

 off of the deposit, when the rivers stood at a level of several hundred feet 

 higher than they do now. 



Bidwill's range is clearly a continuation of the deposits of gravels and 

 clays which are found on the front ranges of the.Huangaroa station, and 

 through which the Euamahunga has burst, leaving the former range 

 isolated. 



It is conceivable that the Euamahunga and its tributaries ran originally 

 along the ranges on the western side of the Wairarapa, until, by the in- 

 crease and spread of their deposits, they gradually forced the bed of the 

 main river to the eastern side of the valley and against the eastern ranges. 

 If at this time we suppose the river to have had a channel over three hun- 

 dred feet above its present level, we can account for the formation of 

 Bidwill's range. Afterwards the river would cut its channel through its 

 own deposits and carry its material further down the valley. 



I am more disposed to believe in the existence of a former barrier and 

 a great extension of the present lake, than to suppose the immense denuda- 

 tion of previous deposits of gravel and clay which is probably involved in 

 any other supposition. The general evenness of the Wairarapa Plain seems 

 to point to a spreading of the surface materials under lake water, and I 

 think the appearance of the lower vaUey, approaching the lake, and 

 including Bidwill's range, gives a similar impression. We might call in 



48 



