THE GEOLOGY OF THE ENGLISH CHANNEL. 183 



H. 41. Trawled 16 miles S. by W. of Eddystone. Weight 5 to 6 cwt. 



A pale-coloured coarse rock witli a rather porphyritic structure, the felspar 

 crystals occasionally about an inch long. Quartz containing rather numerous 

 enclosures, chiefly little cavities with small bubbles ; felspar, rather de- 

 composed, one crystal in the section is a plagioclase, but the larger crystals 

 resemble orthoclase ; white mica ; the section shows a good-sized grain of 

 brownish hornblende ; some dark granules or grains, probably hematite. — 

 T. G. B. 



One Microgkanulite. ^o. 40. 



H. 40. Trawled 22 miles S.W. of Start Point. Weight 2 or 3 cwt. 



The ground-mass a very intimate mixture of quartz and felspar, exhibiting 

 numerous varieties of micrograj^hic structure. Rather rounded crystals of 

 felspar, up to about quarter of an inch in diameter, generally in fair preserva- 

 tioii, and in most cases orthoclase. Smaller and less distinct grains of quartz. 

 Irregular patches of a dark mineral, seen in the section to be a green chloritic 

 mineral, often rendered nearly opaque by the association of brown iron 

 oxide.— T. G. B. 



One Quartz Felsite. No. 43. 



H. 43. Exact locality unknown. Weight about 12 cwt. 



The microscope shows grains of quartz and felspar, and clusters of rather 

 small flakes of biotite, scattered in a microgranular matrix of quartz and 

 felspar, with occasional flakes of biotite or a greenish mineral, possibly a 

 chlorite or a variety of hornblende, with sometimes a certain amount of ferrite 

 staining. The felspar varies much in its state of preservation, some grains 

 being very decomposed, others rather clear. Plagioclase is present. — T. G. B. 



Two Syenite. Nos. 7, 9. 



H. 7. Trawled about 20 miles S.W. by W. of Start Point. Weight about 

 4 cwt. 



A dark green rock of coarse grain, felspars opaque, tinted with pale green 

 and mixed with black hornblende in about equal proportions. Microscopic 

 examination shows the felspars so much decomposed that they are not 

 individually determinable ; many are certainly plagioclase from indications of 

 multiple twinning, Avhether plagioclase or orthoclase is predominant cannot be 

 determined. There is a considerable amount of quartz present, of which 

 much is certainly secondary ; it is seen replacing felspar crystals and originat- 

 ing from their decomposition. The hornblende is green in colour ; by decom- 

 position it gives rise to chloritic matter, with which some epidote is mixed ; 

 epidote may also be seen in the decomposed felspars. Apatite crystals are 

 large, and specially abundant near the hornblende. Ilmenite is also pre- 

 sent.— E. B. T. 



H. 9. Dredged 20 miles S. of Eddystone. Weight from ^ to i cwt. 



The same minerals occur as in No. 7, but it differs by the abundance of 

 quartz, the substitution mostly of chlorite for hornblende, and the obscure 

 linear arrangement of the same. — E. B. T. 



NEAV SERIES. — VOL. VIII. NO. 2. N 



