MODEL OF NEW ENGLAND. 147 



feet. A few miles north of Armidale a plateau surface, 

 similar to that around Armidale, rises rapidly to a height 

 of 4,300 feet, with residuals as high as 5,300 feet on its 

 eastern margin, and this surface is warped very gently 

 to the north and west, but maintains its horizontality to 

 Guy Fawkes, whence it descends rapidly to the coastal 

 area by means of almost impassable gorges. 



Certain most interesting forms occur in northern New 

 Eagland, in the central portion of the Macleay Basin, at 

 the head waters of the Gwydir (between Bingara, Bundarra, 

 Uralla, Elsmore and Tingha), along the Namoi near Ben- 

 demeer, and along the Manning in the vicinity of the 

 Barrington and Gummi "Tops." A brief mention of such 

 of these as occur in the Tenterfield district may be made 

 as they are typical of all the other areas. All occur in the 

 plateau region proper. Here in Northern New England 

 one finds a great wealth of siliceous granites (72-78% 

 silica) associated with basic granites (64 - 70% silica), clay- 

 stones, tuffs, and very siliceous porphyries and rhyolites 

 (72-80% silica). 



The acid granites occur as small and large bosses and 

 stocks, and as bathyliths. The porphyries appear to occur 

 as large Palaeozoic flows. The claystones and allied sedi- 

 ments are of Permo-Oarboniferous Age, in part probably 

 of Lower Marine, Greta, and Upper Marine age. The 

 granites are intrusive into these latest Palaeozoic sediments, 

 and they appear to belong to the period which closed the 

 Palaeozoic sedimentation in New England. 



It is an interesting fact that in the regions containing 

 the acid granite bathyliths and large bosses the general 

 or lowest plateau level 1 is very limited in area and consists 



1 Known as the Stannifer Level of northern New England and the 

 Sandon Level of the southern New England in previous reports of the 

 writer. Both are merely parts of the one continuous level. 



