JOURNAL OF GLACIOLOGY CONCLUSIONS 1. Ablation during the summer months of 1953 at about 1200 m. above sea level, near the upper limit of the supply area of Morsarjokull, averaged 40 mm./day, but 1953 was exceptionally warm. 2. The net accumulation at 1200 m. above sea level on Vatnajokull for 1951-52 was 2'38 m. of firn, which gives an approximate total accumulation for the supply area of Morsarjokull of 34.8 million cu. m. of water. The corresponding figures for 1952-53 are 0·818 m. net

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... ation of firn and 10·8 million cu. m. of water. This indicates the variability of accumulation from season to season. 3. A correlation appears to exist between the rate of flow of the glacier and the weather conditions.The glacier moved faster during rainy weather. The temperature variations during the period of observation were not sufficiently great to affect the movement significantly. 4. The bulge on the medial moraine is attributed to the greater exposure of the rock wall which resulted from the milder conditions between 1890 and 1900. This agrees with the evidence of the rate of movement of the moraine and the evidence of photographs. The discontinuous moraines at the head of Skeidararjokull can be eXplained by a similar process. 5. Evidence for the rapid retreat and thinning of the glacier since 1904 is very marked. The plane-table survey indicates the retreat of the snout to be about 1000 m. since 1904. 6. The remains of a moraine near the Base-camp indicate a possible late glacial extension of Morsarjokull and suggest the line along which this glacier may have been in contact with Skeidararj okull. MS.