38 J. M. Alexander — Summit Crater of Mt. Loa in 1885. 



square miles. The map* of Plate II is reduced from the map 

 sent to the Government as the result of the survey. 



On the southwest side, near the junction of the central cra- 

 ter with the south plateau (C), I found that there had been 

 another eruption from fissures that were still smoking, and 

 that this eruption had sent an immense stream southward tow- 

 ard Kahuku, and had also poured cataracts into the South Cra- 

 ter from all sides. 



I had everywhere observed that there had been great flows 

 from the summit brink down the mountain, and questioned 

 whether the chasm had filled up and overflowed its brim. 

 This, however, turned out to be an incorrect view. The flows 

 have not been from the lowest parts of the brim, but from some 

 of the highest, which could not have been the case in an overflow. 

 The walls of the craters largely consist of loose, old weather- 

 beaten rocks, and large tracts of the plateau are composed of 

 old pahoehoe, that has not been overflowed for ages, which 

 would not be the case if the craters had filled and overflowed. 



These outbreaks from fissures around the rim indicate that 

 the lava has rather poured into the crater than out of it; and 

 that it has flowed from such fissures in vast streams down the 

 mountain side. The question arises, How has the lava risen 

 high enough to pour in extensive eruptions through these fis- 

 sures, almost a thousand feet above the bottom of the crater, 

 without rising in the crater and overflowing it ? The same 

 question has often been asked in respect to the rise of liquid 

 lava to the summit of Mauna Loa without overflowing the 

 open crater of Kilauea, 10,000 feet below. 



While surveying the region, I was extremely interested in 

 the arrangement of the craters ; and now, having determined 

 the situation of more than fifty of them on Mauna Loa, Hua- 

 lalai and Mauna Kea, I have ascertained that there is a method 

 in their arrangement. They are not arranged relatively to the 

 mountain on which they are situated, but relatively to the 

 points of the compass. There seems to have been a series of 

 nearly parallel fissures through which these craters have risen, 

 in lines running from 8. 40 deg. E. to S. 60 deg. E. There 

 are a few arranged in lines running X. 50 deg. E. 



It has been remarked by Mr. W. T. Brigham, in his memoir 

 of 1868 on the Volcanoes of the Hawaiian Islands, that while 

 the general trend of the Hawaiian group and of the major axis 

 of each island is ~N. 60 deg. W., there is no crater on the 

 Islands whose major axis is parallel to this line. " On the con- 

 trary," he continues, " a very interesting parallelism is ob- 



~ To this map the depths of the different parts of Mokuaweoweo below the 

 summit level have been added from estimates received in a letter from the author. 

 The direction of the northern and southern halves of the longer diameter of the 

 crater have also been added on the margin. — J. d. d. 



