Eruptions of Kilauea-— POWERS 
285 
that grew on the surface of the reticulite. The 
reticuhte is a material which could support 
vegetative growth and show very little decom¬ 
position or mixture with humus. 
The second eruption was phreatic, and de¬ 
posits from it are found only on the north and 
east rims. On the slumped rim-blocks below 
Waldron’s Ledge along the Volcano House- 
Halemaumau Trail, are 36 inches of mixed, 
tan pisolitic clay and lithic fragments up to a 
cubic foot in volume. The deposit on Byron’s 
Ledge, at the north end, is similar in make-up, 
but only 6 inches thick. On the Steaming Flat 
(N. Rim 3,950 in Table 2), the deposit con¬ 
sists of 5 inches of pisolitic tan clay overlain 
by 6 inches of layered dust and fine sand. This 
11-inch blanket on the Steaming Flat probably 
would have destroyed existing vegetation. A 
humus layer on its top indicates that some soil 
was formed and a vegetative cover developed 
again before the next eruption. Scattered pumice 
is mixed in with the soil surface in many places, 
and a thin pahoehoe lava flow covered part of 
the north end of Byron’s Ledge during this time 
interval. 
Remnant deposits from the third and fourth 
explosive eruptions range in thickness from 
about 200 inches west of Keanakakoi (S. Rim 
3,650 in Table 2) to 2 inches on the top of 
Uwekahuna Bluff (N.W. Rim 4,075 in Table 
2). A 12-inch section on the Steaming Bluff 
consists of: 
Inches 
Humus layer at old surface 
Fine vitric shards........................................ 2 
Wind-blown vitric shards, dune-like................ 1 
Fine vitric shards grading down to pumice...... 2 
Depositional break 
Pea-size vitric lapilli. 2 
Depositional break 
Fine vitric shards grading down to pumice...... 2 
Depositional break 
Fine vitric shards grading down 
to coarse pumice...................................... 3 
Humus layer, surface of second eruption deposit 
The thickest section of these vitric deposits 
(near Keanakakoi) is in a cliff which is in¬ 
accessible for detailed study. In the walls of 
a gaping surface crack southeast of Cone Peak, 
under the crack flow, the section is 108 inches 
of alternating beds of fine, dun-colored pisolitic 
vitric shards and coarser pumice lapilli up to 
one-half inch in diameter. One mile east (local¬ 
ity E in Fig. 1), the section consists of about 80 
inches of bedded, dun-colored vitric shards; 
another half a mile to the east, just northwest 
of Ahua Kamokukolau, the section is only 6 
inches of unconsolidated, apparently wind- 
drifted, dun-colored vitric shards. 
Following the deposition of these vitric beds 
in the third and fourth eruptions, a complete 
vegetative cover became re-established on the 
windward rim, and pronounced erosion occurred 
on the leeward rim (Plates ID and 4B). 
A series of at least five magmatic explosive 
eruptions next deposited beds of vitric shards 
and pumice totaling over 20 inches on the 
windward rim and over 130 inches on the lee¬ 
ward rim. A thin pahoehoe flow lies on top of 
this series on the southeast rim of Kilauea near 
Keanakakoi. The eruptions were separated by 
time intervals long enough to produce exposed 
surface features but too short to permit the 
growth of vegetative cover on the windward 
rim; however, recovery of the windward rim 
vegetation followed the last of these eruptions. 
The small size and fragmental shapes of the 
shards making up a large part of these thick 
vitric beds and the presence of pisolitic struc¬ 
tures, seem to indicate that the eruptions which 
produced them were more violently explosive 
than the lava fountains which have been ob¬ 
served at Kilauea (or Mauna Loa) in recent 
years. On the other hand, the explosions were 
less violent than some of the phreatic blasts 
which lifted fine material into the upper air 
above the trade winds, because the distribution 
of the vitric beds (Fig. 2B) is typical of deposi¬ 
tion under trade-wind influence. 
The extremely rapid thinning of these beds 
of vitric ash in all directions is very striking. 
Beds 100 inches in thickness half a mile due 
