168 J. D. Dana — History of Changes in Mt. Loa Craters. 



in the fact that the slopes of the western of the mountains in 

 each twin island are partly buried by the more recent lavas of 

 the eastern — Kohala by those of Kea, western Oahu by those 

 of eastern." The order in time of extinction thus derived, 

 which my Report presents, is as follows : 



1. Kauai. 5. Northeast Oahu. 



2. Southwest Oahu. 6. East Maui. 



ch Western Maui. 7. Mt. Kea, Hawaii. 



4. Kohala, on Northwest Hawaii. 8. Mt. Hualalai, Hawaii. 

 9. Mt. Loa and Kilauea. 



ferent sides of the island. On eastern Oahu the valleys are much more exten- 

 sive ; yet still The slopes of the original mountain-cone may he in part distin- 

 guished. And thus we are gradually led to Kauai, where the valleys are very 

 profound and the former slopes can hardly he made out. The facts are so pro- 

 gressive in character that we must attribute all equally to the running water of the 

 land. The valleys of Mount Kea, extending some thousands of feet up its sides, 

 sustain us in saying that time only is required for explaining the existence of any 

 similar valleys in the Pacific. As in Tahiti, these valleys in general radiate from 

 the centre, that is, take the direction of the former slopes ; they often commence 

 at the central summits and terminate at the sea-level instead of continuing be^ 

 neathit." (pp. 384. 385.) 



"With literal truth, therefore, we may speak of the valleys of the Pacific 

 islands as the furrowings of time and read in them marks of age. We also learn 

 how completely the features of an island may be obliterated by this simple pro- 

 cess, and even a cluster of peaks like Orohena, Pitohiti and Aorai of Tahiti, be 

 derived from a simple volcanic dome or cone. Mt. Loa alone contains within 

 itself the material from which an island like Tahiti might be modelled that should 

 have nearly twice its height and four times the geographical extent " (p. 391.) 



■ : We need add little in this place on the capabilities of running water after the 

 statement, based on mathematics, that the transporting power varies as the sixth 

 power of the velocity. If we remember that these mountain streams at times in- 

 crease their violence a million-fold when the rains swell the waters to a flood, all 

 incredulity on this point must be removed." " There is everything favorable for 

 degradation which can exist in a land of perpetual summer ; and there is a full 

 balance against the frosts of colder regions in the exuberance of vegetable life, 

 since it occasions rapid decomposition of the surface, covering even the face of a 

 precipice with a thick layer of altered rock, and with spots of soil wherever there 

 is a chink or shelf for its lodgement. The traveller ascending a valley on one of 

 these islands on a summer day, when the streams are reduced to a mere rill which 

 half the time burrows out of sight, seeing the rich foliage around, vines and 

 flowers in profusion covering the declivities and festooning the trees, and observ- 

 ing scarcely a bare rock or stone excepting a few. it may be. along the bottom of 

 the gorge, might naturally inquire with some degree of wonder. Where are the 

 mighty agents which have channeled the lofty mountains to their base ? But 

 though silent, the agents are still on every hand at work : decomposition is in 

 slow but constant progress ; and the percolating waters are acting internally if 

 not at the surface. MVreover. at another season, he would find the scene changed 

 to one of noisy waters careering along over rocks and plunging down heights with 

 frightful velocitv, and then the power of the stream would not be disputed." 

 (p 389.) 



* The wonderful valleys of Kohala are given on the map of Hawaii, making 

 Plate 1 of this volume. They are some of the deepest, most abiupt, and most 

 beautiful in the islands, and are well described in Mi*s Bird's Six Months in the 

 Sandwich islands. Subsidence may have been coucerned in the origin of part of 

 them. 



