ORIGIN OF LATERITE IN NEW ENGLAND DISTRICT, N.S.W. 235 



laterite. From here to the summit the slope steepens to 

 an angle of 20° to 30°, and the rock becomes harder and 

 more slaggy. The top is covered with scrub from six to 

 seven feet high, rendering it difficult for the observer to 

 get a good view of the general shape of the hill. The 

 latter, however, may be gathered from the geological map, 

 which shews the hill to be conical, the edges of the hill top 

 being elevated above its centre, so as to enclose a hollow, 

 the bottom of which is about forty feet below the level of 

 the rim. The basin, or crater, so enclosed is a quarter of 

 a mile in diameter. To the south-east the crater ring has 

 been broken down, probably during a volcanic outburst ; 

 and the breach has been furtlier deepened by the Forest 

 Creek, which has its source within the crater. A small 

 natural section is thus afforded of the internal structure of 

 the hill. In the banks of the creek hard masses of spongy 

 laterite, three to four feet in diameter, are seen to overlie 

 a soft purple lava, which here forms a central core in the 

 bottom of the crater. Following the creek down, the 

 observer passes gi-adually below the level of the soft lava 

 on to a small stream of hard stony basalt, which has 

 evidently welled up from some point beneath the crater. 

 The hill, therefore, possesses all the essential featui'es of a 

 volcanic crater, and may consequently be considered an 

 extinct volcano." 



In Portion 724, Parish of Strathbogie North, County 

 Gough, laterite forms the rim and bottom of a semi-cii'cular 

 basin, about six chains in diameter, and evidently an extinct 

 crater, from the centre of which a miniature stream of 

 basalt takes its rise. Hills of this class which have been 

 much denuded pass by insensible gradations into promi- 

 nences of the next variety :— 



(l)) Sugarloaf, flat-topped liills, destitute of a central de- 

 pression at the summit. Crescentic and sugarloaf hills, 

 with summits either flat or shewing very slight depressions 

 occur in tlie Parish of Astley, County Gough, where they 

 rise only about fifty feet above the general level of the 

 surrounding lava steams ; and at Vegetable Creek similar 

 hills occur, but they have suflered more from the effects of 

 denudation. 



2. Ridges. — Elongated ridges, having one side more or less 

 steep, and having a slope of from 20° to 30°. The elongated 

 ridges of laterite are more difficult of explanation. A typical 

 example of a ridge of this kind adjoins the " Gap" crater 

 just described. This ridge runs south for half a mile, and 

 then south-east for another half mile. The summit is from 

 one to two chains in \vidth, and formed of laterite. The 



