122 



Marble, or Metamorphosed Limestone. 



In no case have I been able to trace this class of rocks con- 

 tinuously throughout the entire extent of the district. This 

 fact at ouce leads me to conclude that their deposition was 

 more restricted by local influences than that of the sands now 

 constituting the quartzites. I have invariably found that 

 abrupt depressions of the surface iudicate their lines of out- 

 crop. The beds have a teudency to decay pretty uniformly 

 with the intercalated clay-slate, and in the low-lying parts 

 they are covered to a considerable depth with recent 

 debris. It is, therefore, only by the aid of these depressions 

 and where they stand out in bolder relief on the ridges, that 

 their outcrops can be traced extensively at all. 



Beginning from the west, the first in order of the Mumio 

 Para marbles is a compact grey stone, overlying, at a distance 

 of 30 feet, the eastern quartzite band of the Mill series. In 

 Section 4173 it attains no great thickness, and I have not been 

 able to trace it further south than into Section 1678. But by 

 the aid of the above-mentioned surface depressions I have fol- 

 lowed the line of outcrop north into Section 4350, where a 

 very good section of the outcrop is exposed, averaging a thick- 

 ness of from 12 to 20 feet, and further extension in this 

 direction is indicated by the presence of surface blocks of the 

 same kind of stone. 



No. 2. A. black stone, somewhat slaty in character in places, 

 is situated about 12 chains east of the former. It follows a 

 north and south line into Section 4178 ; by the help of the 

 surface depressions I have been enabled to follow the line of 

 strike south into Section 4215. The limited exposure of the 

 bed prevents accurate measurement of its thickness being 

 taken, but in Section 4173 it is estimated at from 30 to 40 

 feet. 



No. 3. Intersects cross section in Section 3266. Its 

 position is only inferred by a chain of surface depressions, and 

 a few small blocks strewn over the adjoining surface. 



No. 4. Another stratum peeps out, though faintly, in Sections 

 4146 and 4350. 



No. 5. As shown on map, passes through Sections 3347, 

 3348, and 3349. 



No. 6. Still further east another band occurs in Section 

 1032 and 1033, the strike of which is about parallel to that of 

 the eastern quartzite band. No. 5, in passing south, from 

 about five chains within Section 3348, trends in the same 

 direction. 



Also on a spur overlooking the bed of the river, in Section 

 1787, an impure marble has been detected. 



Origin. — The occurrence of limestone suggests the proba- 



