Vol. 68.] COMPOSITION^ OF THE AECTIC BED. 245 



but fairly numerous calcareous sporangia of Chara. Ostracods, 

 foraminifera, and small gastropods were also present. The sandy 

 residue amounted to 49-1 per cent, of the sample. It was coarse 

 in grain, and included 8'4 per cent, of stones measuring over 2 mm. 

 in diameter ; only two of these exceeded 1 cm. All the stones were 

 Hint, and most of them were siibangular; many had a lustrous 

 black-stained surface, while the interior was grey or whitish flint. 

 The sand contained 4-3 per cent, of calcareous matter, rather 

 numerous grains of quartzite, and small amounts of flint, felspar, 

 ■and glauconite. 



The heavy minerals amounted to O'G per cent, of the sand. 

 The greater part of the concentrate consisted of dark-grey grains 

 which appeared to he an intimate mixture of pyrrhotite and 

 pyrites ; they were lifted in a weak electro-magnetic field, and 

 were only partly soluble in hydrochloric acid, but completely so 

 in nitric. A little free pyrrhotite and pyrites also occurred, the 

 former in dull earthy-looking grains, the latter in spherical and 

 irregular aggregates. The remaining heavy minerals, 0-07 per cent, 

 of the sand, consisted of garnet, ilmenite, zircon, tourmaline, 

 staurolite, hornblende, epidote, kyanite, rutile, andalusite, pyroxene, 

 and apatite. 



Sample 5 was a grey sandy loam, containing a small amount of 

 vegetable matter and a few ostracods, foraminifera, and broken 

 gastropod-shells. Sand formed 50' 1 per cent, of the sample. The 

 largest grain was a splinter of flint 6 mm. long. Calcareous 

 matter amounted to 11"5 per cent, of the sand; flint and quartzite 

 were fairly common, but felspar and glauconite less so; one grain 

 of brown biotite and a few flakes of white mica were noted. 

 On treatment with bromoform, 0*55 per cent, of the sand sank. 

 Of this, 0-26 was pyrrhotite, a considerable amount limonite, a 

 smaller proportion pyrites, and 0-09 per cent, detrital heavy 

 minerals. These last consisted of garnet, tourmaline, staurolite, 

 epidote, zircon, hornblende, kyanite, ilmenite, rutile, and andalusite. 



Sample 6 was a grey sandy loam, Containing small amounts of 

 vegetable matter, ostracoda, foraminifera, and gastropoda. The 

 sandy residue amounted to 49*3 per cent., and contained 11*5 per 

 cent, of calcareous matter. Flint and quartzite were present in 

 some abundance, as also small amounts of felspar and glauconite. 

 The biggest grain observed had a length of 4 mm. 



The heavy minerals included 0-27 per cent, of pyrrhotite, some 

 limonite, a little pyrites, and 0-09 per cent, of other minerals 

 (namely, garnet, tourmaline, staurolite, epidote, zircon, hornblende, 

 kyanite, ilmenite, rutile, and andalusite). It will be noticed that 

 this sample is practically identical in composition with Sample 5. 



The principal points in the foregoing descriptions are summarized 

 in the following tables. 



