ITDENBUEG AND DE KAAP, TEA^SyAAL, SOUTH AFEICA. 



581 



i'. South of the Spitzkop mountain is " Grey's Creek," near the 

 mouth of which is an old heading, driven 60 feet into the hill. 

 This shows a seam of quartz from 1 foot to 2 feet thick, between 

 decomposed chalcedolite above and brown sand (? decomposed dio- 

 rite) below. These beds dip W. at an angle of 5", and underhe the 

 shales that form the high ground on the west. The quartz seam 

 here, interstratified with the beds, varies (where opened) from 1 foot 

 to 2 feet in thickness, and yields an average of 3 oz. 12 dwt. of 

 gold to the ton. 



j'. Upon the farm called "Spitzkop," north of the mountain of 

 that name, are numerous cuttings made by the miners, nearly all 

 in shales and flagstones. Towards the east side, however, the more 

 sihceous beds come in, and where exposed in some open mines, 

 they are much decomposed, especially the lower few feet resting 

 upon the saddle of a decomposed diorite dyke. On the east side 

 of the farm the so-called "rotten-reef" has been rather exten- 

 sively worked in two claims, where it rests upon the saddle-back 

 of a decomposed diorite dyke. The numerous quartz-leaders in 

 the shales "vary even in a few feet from 3 inches to ^ inch in 

 width ; they vary slightly also in dip and direction. Their average 

 width may be taken as 1^ inch : their general dip S. 50° to 55° ; 

 and general direction E. to "W. The direction of the dyke being 

 W.N.W., the leaders strike it at an angle of about 20 degrees." 



In the shales are very many thin veins of quartz, more or less 

 vertical, which, in the lower 3 to 5 feet, are broken up and indis- 

 criminately mixed with the matrix, thus forming a so-called " rotten- 

 reef." This term is also applied to the several feet of strata exposed 

 above, although less decomposed. 



Pig. 2. — Section of " Rotten-Reef,^^ Sjpitzko]). 



Shaft, 25 ft. deep. 



a. Tilted shales. h, Diorite Dyke. 



c. The " rich layer." 



The section, fig. 2, shows a shaft 25 feet deep down to the dyke, 

 along which a drive has been made 35 feet to the jN'.jN'.AV., following 

 the downward dip of the " rich layer," here consisting of 3 feet of 

 " rotten-reef," with from 1 to 2 feet of poorer "wash" between it and 

 the dyke. The shaft is sunk through contorted and partly decom- 

 posed shales, with auriferous quartz-leaders. 



