iilegular strata of scoriae, and (he 
later splitting and diking of the 
whole mass. 
feuch dikes I have found as a char-* 
acteristic accompaniment of the in- 
teiioi scoiiaceous cores of our moun¬ 
tains. Many persons must have ob- 
served the very fine specimen of a 
basaltic dike intersecting the road 
down the Nuuanu pali. Some splen¬ 
did specimens cut obliquely across 
the inner scoria piles of Olovvalu 
and Ukumehame canyons on West 
Maui, striking in parallel lines uu- 
deviatingly across ridge and chasm, 
and rearing sharp crests above the 
heights. Some of our Nihoa party 
may remember a succession of high 
ridged perdendicular steps on the 
main left hand, slope. Those were 
the lower faces of several parallel 
dikes cutting across the ridge. 
From the great number of these 
dikes, I infer a very protracted pe¬ 
riod of volcanic activity. From the 
closeness with which they stand, 
perhaps forty or fifty cutting across 
the island, I infer that we are look¬ 
ing far down in the deep heart of the 
former dome, where dikes would be 
thickest. 
As to probable subsidence, some¬ 
thing may be inferred from the fact 
that all outlying peaks and ridges 
have disappeared from what the 
jiresence of the sharp, hard, thick-set 
dikes proves to have been once a 
dome of considerable extent at least. 
Kihoa seems lobe the sole submerged 
pinnacle. 
The peculiar contour of the ridges 
running down towards each other 
seems very significant. This is pre¬ 
cisely the contour of the heads of 
the leeward valleys descending from 
the peaks on either side of Nuuanu 
Valley. It is the amphitheater form 
which Captain Dutton shows to be 
, the natural evolution of the heads of 
ravines of atmospheric erosion. 
Take the top of Konahuanui; sink 
it slowly to within 900 feet of its 
twin summits. Let the waives mean¬ 
time be eating away the bases of its 
extremely steep Koolau, Nuuanu and 
Manoa sides, until they become per¬ 
pendicular, while the sloping south¬ 
western valley is defended from the 
sea by its protecting side ridges. In 
the course of the ages Konahuanui 
has become the somewhat smaller, 
but very exact counterpart of Nihoa 
in every particular, both of position, 
contour and structure. 
Sailing from Nihoa at 4 p. m., w e 
made the small island of Kan la, 
twenty miles southwest of Niihau, 
at 7 a. m., and spent two hours and 
more in making the circuit of the 
island and landing a party in pur¬ 
suit of the birds which swarmed much 
as at Nihoa. Kan la is a beautiful 
specimen of the cinder-cone, about, 
the size and form of Punchbowl 
cut in half, the lower and windward 
half destroyed by the waves. is... 
beautiful compact laminated strata oi 
true,yellow cinder showed the round 
eu 
“onion-skin” form admirably, much 
like the sea face of the lower Ivoko 
Head. The contrast with the irr 
egu- 
Vtpa.'. A- -5 
V 
•7- 
lar but quite horizontal strata of Ni¬ 
hon’s gray and black scoriae was 
most marked. Lekua, which we 
skirted in the afternoon, exhibited a 
formation similar to Kaula, but main¬ 
taining about 200 degrees of its cir¬ 
cle, instead of the 140 degrees of the 
latter. The lamination on the south 
incline of the higher part is exqui¬ 
site. Both these crater cones of Le- 
hua follow the common law of all 
such formations in these islands, 
that their highest side is to the west, 
whither the prevailing trade wind 
Lehiia, Kaula and Molokini opening 
to the winds and surges. 
In contrast with this law of the 
cinder-cones, and in accordance with 
the prevailing law of our older and 
deeply eroded ridges and pinnacles, 
Nihoa presents its high and perpen¬ 
dicular side to the wind, and its 
sloping and indented side to the lee¬ 
ward, as does Konahuanui. 
Evidences of a slight recent eleva¬ 
tion, following a long period of sub¬ 
sidence, are quite marked on Oahu, 
and I think on Kauai and perhaps 
usually pushes the falling rain of / NHha'u. k I therefore looked for fl¬ 
ashes and lapilll during the brief ex- : deuce of Vueh possible recent eleva- 
pio-ion, building up to leeward a tion at Nihoa., blit discovered none 
compact laminated pile of the ejecta, 
while the windward side is low, and 
if exposed to the waves, soon washed 
away, leaving a crescent form like 
whatever. . Such tokens, however, 
must easilyeludeobservation on so 
precipitous and unsheltered ashore. 
Very respectfully, 
' 'Net .: 1 
SERENO E. 131SIIO IN 
Honolulu, July 31, 1885. 
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