31, 
Volcanic ash zones, A series of samples of volcanic material 
from deep sea cores is being studied by Professor Erik Norin, Mineral- 
ogiska Institutet, Uppsala, Sweden, 
Meteoritic dust, About 50 meteoritic spherules have been found 
in the cores, Several were studied by Dr, J. D. Buddhue, Institute of 
Meteoritics, University of New Mexico, These have been described in 
the monograph ''Meteoritic Dust", J, D, Buddhue, The University of 
New Mexico Press, 1950, 
Rocks. A collection of several hundredweights of boulders 
dredged from depths approaching 4575 m, over the Mid-Atlantic Ridge 
has been analyzed by Dr. S, J, Shand, Columbia University. Some of 
these boulders are of limestone and the large proportion consists of 
eruptive rocks referable to the groups holocrystalline gabbroic rocks, 
basalts (pillow lavas) with and without olivine, and serpentines, The 
knowledge of composition of the Mid-Atlantic Ridge has been derived 
hitherto from the islands and island groups which are scattered at long 
intervals along its course, On these islands the dominant rock is basalt, 
According to? Dr. Shand the collection confirms the predominance of 
basalt and makes at least two notable additions to the record, namely an 
abundance of serpentine and a mylonitized gabbro. (For detailed descrip- 
tion and analyses see ''Rocks of the Mid-Atlantic Ridge" by S. J. Shand, 
Jour, Geol. vol, 57, pp. 89-92, 1949; and ''Age of a Mid-Atlantic Ridge 
Basalt Boulder", D, R, Carr and J. L. Kulp, Geol, Soc. Am, Bull., vol, 
64, pp. 253-254, 1953.) 
