536 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [JuilO 6, 



inches to 3 feet in width, running somewhat about east and west, 

 dipping, although mostly south, at various angles, and composed of a 

 " voughy " or cavernous quartz, with crystals often coated with 

 brown iron-ore, and copper and iron-pyrites. They often present a 

 very irregular appearance, being split up in small branches. 



4. A great number of " slides " or faults, of from 3 inches to a 

 foot in width, dipping at various angles, and mostly with an east 

 and west bearing. There are some, however, called "caunting" 

 slides, running north-east and south-west. They are formed, no 

 doubt, by the dislocations of the adjacent "country," consisting 

 as they do of decomposed killas, as if the rock had been ground 

 together and then acted on by water. 



Lastly. Pour cross courses (north and south veins), one only of 

 which is of any consequence. It averages 3^ feet in width, is 

 nearly perpendicular, and is filled in with decomposed killas and 

 masses of quartz. 



The influence which these lodes and veins exert on each other 

 will be seen in the transverse sections (figs. 1 & 2), — the tin -lodes 

 (that is, Cowling's) and the Mat lode being thrown by the ** down- 

 rights," gossans, and slides, the " downrights " by the gossans and 

 shdes, and the gossans by the slides, although there does not happen 

 to be an example in the section of the latter case. A southern 

 dip in the traversing vein throws the lode traversed up in going 

 from S. to N., and a perpendicular or northern dip depressing it ; 

 in other words, the " hanging wall " of the traversing vein seems to 

 have moved down, or the " footwall " to have moved up — the wider 

 the traverse the further the -heave. The cross course masters all the 

 east and west veins, throwing them to the right hand a distance of 

 from 20 to 30 fathoms, the tin-lodes being thrown further than 

 those of more recent formation. The cross courses, however, have 

 to yield to the " caunting " slides, as seen in an adjoining mine, 

 which throw them a little on the side of the acute angle. The 

 mineral productiveness of the tin -lodes is increased by the proximity 

 of the gossans, but not by that of the slides. 



As before stated, the dip of the "country" is generally pretty 

 regular ; yet still very marked evidence of disturbance can easily be 

 perceived in some places, the line of stratification presenting a very 

 wavy form. This is especially seen sometimes near the gossans 

 and slides, where, at the immediate point of junction, the beds of 

 killas are found to bend up on one side and down on the other, 

 affording additional proof of the direction of the heave. The relative 

 ages of all these veins may be at once determined from the above 

 facts. Taking the well-known law, that a lode or vein traversed is 

 older than the one traversing it, as a guide, we shall have : — 



1, Tin-lodes. 4. East and west slides, 



2, "Downrights." 6. Cross courses. 



3, Gossans. 6. "Caunting" slides. 



Slides, according to Carne, are generally considered to be of more 



brown iron-ore. At St. Agnes the meaning attached to the term is somewhat 

 different. ' ' 



