EXPLANATION OF THE PLATES.
PART II.
Veins of granite and porphyry traversing the schist of Cruachan.
Fig. 1. Passage of porphyry veins through schist already traversed by veins of granite.
Fig. 2. A similar circumstance, representing at the same time the parallel and adjoining position of two veins of differently coloured porphyries.
Plan and Sections of the mine of Huel Peever, shewing the interruptions that have occurred to the veins in that mine The ground plan, Fig. 1. represents the effects produced by the cross courses intersecting the veins that run in the direction of east and west. The transverse section, Fig. 2. shows the interruptions among themselves of the veins that run in an east and west direction, occasioned by the various degrees of inclination of their underlie. The tin vein is intersected by the copper vein, and they are both again affected in a similar manner by the two slides.
The longitudinal section is explained, p. 144.
Tunnel of the Tavistock Canal.
The various beds and lodes met with in working through the hill are here represented, as well as the number of shafts sunk in the process of making the Tunnel.
Map of Sky, described p. 156.
