In this study of brief, intense warm events in the Early Pliocene, the authors encountered evidence for at least one major glaciation during this time interval. They measured the percentage of carbonate, the percentage of opal, and the (Ge/Si) (sub o) pal for the Lower Pliocene sequence of hole 737A. A figure shows the results of this study; because the percentage of carbonate was generally low through this interval, it is not shown. The percentage of opal, on the other hand, is generally high, ranging between 50 and 60%. Between approximately 40 to 60 m depth, the percentage concentration of opal drops to almost 20%. This drop is accompanied by a change in (Ge/Si) (sub o) pal from a high of 0.80 to a low of 0.50. This event occurs between the Nunivak and Sidufjall subchrons of the Gilbert chron and is tentatively dated at about 4.5 mya. Using the criteria stated above, the authors interpret this to be a glacial event.