THF VOYAGE OF H.M.S. CHALLENGER. 
loS 
ileposits being called Green Muds, altliough very pure glauconitic muds and sands were 
dredged in the shallow water of tlie Agulhas Bank, to be referred to in describing the 
section from Cape of Good Hope to Prince Edward Island. 
SfOid}/ Point to Falkland Islands. — On the return voyage the Challenger entered 
tlic Atlantic by the Strait of Magellan. The deposit at 55 fathoms, as well as in two 
other soundings, 70 and 110 fathoms (see Chart 42), was a coarse sand, the grains about 
one millimetre in diameter, consisting of quartz, jasper, felspars, mica, hornblende, augite, 
glauconite, pumice, and particles of crystalline and schistose rocks. 
Falkland Islands to Rio de la, Plata. — The deposit in 1035 fathoms in this section 
was a sandy gravel (see Chart 42). The trawl line carried away and the trawl was lost, 
but the tow-net attached to the line at the weights contained some of the gravel. The 
larger particles were from 1 to 2 cm. in diameter, brown coloured, flattened, ellipsoidal, 
<lerived from ancient continental formations, such as schist, gneiss, arkose, and sandstone, 
together with milky and hyaline quartz, felspar, augite, magnetite, microcline, horn- 
blende, and glauconite. The glauconite was globular, ovoid, elongated, or vaguely 
triangular, with rounded angles ; many of the particles were not so homogeneous as true 
glauconite, and appeared as aggregates of minerals cemented by a green matter. Some- 
times they showed a schistoid structure, and often it was difficult to say whether the 
fragments were glauconite or pieces of rocks strongly impregnated with a chloritic sub- 
stance. iUixed up with the above-mentioned sandy particles were calcareous Foraminifera, 
fragments of Molluscs, Brachiopods, Echinoderms, and Polyzoans. In 2040 fathoms the 
deposit was a Globigerina Ooze containing 33 per cent, of carbonate of lime. At 2425 
fathoms there was a Blue Mud containing about 40 per cent, of mineral particles with a 
mean diameter of 0T2 mm., and 6 per cent, of carbonate of lime derived from bottom- 
living Foraminifera and small teeth of fish, the remainder of the deposit being composed 
of the remains of siliceous organisms, fine mineral particles, and clayey matter. 
In GOO fathoms the deposit was a Blue Mud, green-grey in colour, containing 12 per 
cent, of carbonate of lime. In the sounding tube and in the trawl there were several 
small concretions, from 1 to 3 cm. in diameter, nodular, more or less elliptical, and vary- 
ing in colour from grey -green to yellow-green. They were agglutinations of the clastic 
materials forming the deposit, cemented together by a clayey matter united with a 
chloritic mineral, but were not very coherent. Cut into thin sections, they were seen to 
be fonned of angular fragments of quartz (TO to 0‘5 mm. in diameter), of felspars, some 
of which were triclinic, of hornblende, of glauconite, and of garnet. The amorphous 
matter cementing this sand was finely granular, and impregnated with a green or 
yellowish chloritic substance, with vague outlines and non-birefrangent, the same as that 
obsor\'ed upon the isolated grains of the mud. With these sandy agglutinations were 
associated rounded elliptical fragments with a diameter of from 1 to 2 cm.; they were 
green, fine grained, could be scratched with steel, and at first sight appeared to have the 
