THE GEOLOGY OF THE ENGLISH CHANNEL. 131 



brown, apparently existed in ophitic form ; it is now almost entirely 

 replaced by hornblende. Tlie hornlilende is cliietly pale green, with a 

 slight blue shade and orange-brown tints along cracks and cleavages. 

 The titanic iron ore is entirely associated with the hornblende, and is 

 present in large forms and l)ranching growtlis. Chlorite occurs in 

 fairly large areas, and exhibits marked pleochroism from pale brown 

 pink to pale bluish green. The felspars are pale pink, rather fresh in 

 appearance, but sometimes traversed along cleavages by chlorite ; 

 they have a tendency to elongated parallelogram section. Quartz 

 shows good crystal outline. 



M. 14v. S. 24° W. Edd., 20 miles. 



A small hard pebble, distinctly green in colour, and having small 

 somewhat vesicular looking cavities on the surface. 



In section, seen to be a network of small lath-shaped felspars set in 

 a grey and green ground-mass. Chlorite is disseminated throughout 

 the slide, and the larger patches, which are not infrequent, are 

 evidently after augite, as they are associated with unaltered remnants 

 of the latter mineral. Calcite occurs, not only mingled with the 

 ground-mass, but also in larger patches; the solution of these has 

 probably left the cavities on the surface of the pebble. There are two 

 or three recognizable crystals of ilmenite and scattered black grains 

 that are either this mineral or magnetite. 



M. 15c. S. 2T W. Edd,, 20-3 miles. 



Greenish hornblendic rock. 



Large patches of very pale hornblende. Between these a fibro- 

 granular ground-mass of low double refraction, prismatic and basal 

 sections of zoisite of sufficient size for discrimination occur rather 

 freely. Some iron ore. What other minerals may be present in 

 minute forms cannot be determined. 



Zoisite-amphibolite. 



M. 22c. S. 25° W. Edd., 21*9 miles. 



Dark green rock, massive hornblende. 



Shows a very little felspar, and a few patches of augite. In the rest 

 it consists of reedy hornblende of very varying tint, from almost 

 colourless to olive-brown and l:)lue-green, all in light shades. 



GRANITOID ROCKS 



M. 31. S. 25° W. Edd., 15 miles. 



Granitic texture. Brown and black, ditto brown. 

 Felsitic. Brown, fine-grained, granular. 



