Age determinations by the C14 method have shown that dolomite in surficial sediments of Deep Spring Lake, California, is virtually recent. The dolomite crystals are generally less than 1 μ on the rhombohedral edge. The newly formed dolomite is calcium‐rich, has a range of compositions, is very poorly ordered, and has weak basal reflections. A small amount of detrital dolomite is also present, which is compositionally and structurally distinct from the newly formed dolomite. The average growth rate of individual crystals is of the order of hundreds of angstroms per thousand years; the rate of growth of rhombohedral edges of the crystals has been roughly constant with time. Extreme slowness of growth of individual crystals seems essential for the formation of the ordered dolomite phase at low temperatures. A slow net rate of deposition appears essential to the development of the ordered phase before final burial. Ordering probably takes place near but slightly beneath the surface of the growing crystal. Conditions in Deep Spring Lake favorable for the formation of dolomite were initiated near the close of the pluvial period.

Since 1948, carbon‐14 measurements on the bicarbonate of ocean water samples from the Pacific and Indian oceans have been carried out at the Scripps Institution of Oceanography, La Jolla, California. Previous reports of the results of these investigations have been confirmed and amended by many recent measurements. The method of extracting CO2 from ocean water has been modified and perfected over the past years. The most notable results of the measurements concern the 14C content of deep ocean water which can be interpreted unambiguously by considering the aging of the water during the time of movement from the Weddell Sea eastward and then northward into the North Pacific Ocean.

Results of C14 determinations in surface water from the Pacific were in agreement with those reported by Rafter and Fergusson. However, abnormal C14 concentrations seem to exist locally, for which no oceanographic explanation can be given. It seems premature to draw conclusions from existing determinations as to the rate of increase of C" in surface ocean water resulting from the uptake of C14 produced in the atmosphere by atomic bombs.Samples from a constant depth of about 3,500 meters show a C14 content decreasing from south to north. This decrease may be attributed to radioactive decay of C14 during the time of migration. From this the northward component of the rate of water movement of about 0.06 cm/sec can be calculated. The ClS determinations, for the purpose of correcting the C" values for isotope fractionation effects. were found to be remarkably consistent, although made on reburned acetylene.

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