ROCKS AT THE PALI 35 



pass up a canyon whose sides exhibit volcanic layers dipping gently 

 toward the harbor. On reaching the place where vegetation is notably 

 more vigorous, the red earths increase in amount, and are probably in 

 part at least the products of an old crater, not named, a mile or more 

 from the summit. This has been broken down on its southerly side- 

 Nearer to the gap are thick deposits of an agglomerate, having a red 

 clayey cement, which has been cut away at the summit and is very ex- 

 tensively spread out on the eastern side. Its point of ejection is not 

 known. Doctor S. E. Bishop thinks there must have been an orifice at the 

 very notch through which it has been poured out. The notch is being 

 enlarged by removing the old basalt, which is finely exposed in horizontal 

 layers, soon seen, as we pass downward, to have been cut b}^ dikes of a 

 fine grained compact basalt, sparingly spotted by chrysolite. 



The photograph, reproduced as plate 5, of the ledges at the extreme 

 southeast angle in the Pali road, three-fourths of the descent down, gives 

 some idea of the relations of several of the different kinds of rock seen. 

 From the carriage to the extreme left the principal rock is an amygda- 

 loidal basalt, containing opal, quartz, natrolite, prehnite, and thom- 

 sonite. One mass of quartz, supposed to come from near this spot, is 

 amorphous, with small crystalline cavities, and is about 8 inches in 

 breadth. This is the largest piece of quartz I have seen from any part 

 of the archipelago. This amygdaloid has been cut by several narrow 

 dikes, standing vertically, and traceable down the road for 200 feet. At 

 the angle the walls of the dikes are coated by what looks like obsidian, a 

 quarter of an inch thick. It is a glazed coating produced by the contact 

 of the retaining walls on the igneous mass. The amygdaloid is some- 

 what columnar. The rough rocks on the right-hand side of the road 

 represent the upper end of a laccolite of chry soli tic basalt, notable for the 

 considerable size and great number of the bunches of chrysolite, as well 

 as by its columnar structure. On both sides of it and above may be 

 seen an agglomerate containing basaltic fragments, and particularly in- 

 teresting pebbles of chrysolite, which are soft by weathering. At some 

 places it has been cut and again traversed by beds of fine-grained basalt, 

 seemingly the equivalent of the vertical dikes mentioned high up toward 

 the summit of the road. In other places there is a glazing upon the sur- 

 face of the agglomerate at its contact with a later ash. This ash clinker 

 or lapilli is of a red color, is very abundant, and has been cut by the 

 road in some places to the depth of 90 feet. It has poured down the 

 steep hillside at an angle of 45 degrees, and rests unconformably upon 

 every other kind of rock. It is bright -red in color, and is very similar 

 to the ashes of some of the Laeloa craters. It is so obviously of very 

 modern origin that it is strange that any observers should ever have 



