378 
THE VOYAGE OF H.M.S. CHALLENGER. 
1. The orgauisins which in many instances cover them continue to live even while 
the depositions are taking place. This shows evidently that in the ordinary 
progress of the phenomena only minute particles of the substance are deposited 
during the life-period of these animals. 
2. All the pelagic deposits, in which these nodules are found in abundance, must 
increase much more slowly than the terrigenous deposits, and in all those 
pelagie deposits, like the Eed Clays, where the calcareous organisms are wholly 
removed in solution, the rate of deposition must be exeeedingly slow. 
3. The highly-altered state of the basie and other fragments of volcanic glass shows 
that they must have lain a long time in the surface layers of the deposit 
exposed to the action of sea- water. 
4. The greater abundance of sharks’ teeth, bones of Cetaceans, crystals of phillipsite, 
cosmic spherules, in the areas where nodules are numerous, than in other 
deposits, points also to a slow rate of accumulation, for, a priori, there is no 
reason why these should be more abundant in these manganese regions except 
the fact that they are not covered over and masked by such an abundance of 
foreign materials as at other points of the deep sea. That some of the sharks’ 
teeth, for instance, are covered by deep layers of manganese, while others lying 
alongside of them in the deposit have little or no manganese, indicates that some 
have lain on the bottom for a much longer time than others, and that there has 
been but little increase in the thickness of the deposit during the interval. 
5. We have pointed out that nodules sometimes occur in Globigerina Oozes, as for 
instance at Station 297, but here they are not accompanied in the dredgings 
and trawlings by sharks’ teeth, earbones of whales, zeolites, nor cosmic spherules, 
apparently from the more rapid accumulation due to the presence of the 
Foraminifera. In this and other deposits there are, however, many fragments 
of altered basic volcanic glass, which indicate proximity to submarine eruptions. 
III. Glauconite. 
Among the minerals of modern marine deposits, glauconite is one of the most intere.st- 
ing as well as one of the most widely distributed. This interest arises from the facts that 
it is one of the restrictecl number of silicates formed at the present day on the sea-bed, 
and that it is not universally distributed over the floor of the ocean, but is limited to the 
deposits forming along continental shores. The glauconitic grains found in marine deposits 
pre.sent, moreover, Ixjth in form and size, a complete analogy with those found at different 
horizons in the geological series of rocks, from the Cambrian period up to the most recent 
Tertiary layers. We are thus dealing with a mineral species that i)lays a very con- 
