DISCUSSION 265 



munication with the conduit of the main volcano. This question needs 

 to be determined before the example cited can be admitted as evidence 

 on either side, in reference to the source of the water- vapor of volcanoes. 

 I am inclined to think that the secondary eruption referred to was a 

 superficial phenomena, similar to the surface eruptions in beds of hot 

 debris, recently observed on Martinique and Saint Vincent. If this sug- 

 gestion should prove correct, the example referred to on Etna becomes 

 just as strong an argument in favor of the meteoric source of supply of 

 volcanic water as is now claimed for it by the opponents of that view. 

 The quantitative measures of Fouque seem to carry weight, but I doubt 

 if the quantity of water mentioned is as great as was discharged into the 

 air during a period of 100 days by any one of several superficial or 

 ' debris craters ' on Martinique or Saint Vincent during the earlier stage 

 of the recent period of activity of the volcanoes on those islands. 



" . . ., on page 251, we are told : ' The variety of gases in volcanic 

 eruptions can not all be derived from meteoric water, as some of them 

 are not contained in sea water.' In the same paragraph, however, the 

 statement is made that ' the ocean itself is the product of volcanism.' 

 These two statements do not seem to harmonize; if the ocean is a pro- 

 duct of volcanoes, why are not the products known to be given out by 

 volcanoes found in the ocean. 



"Color of rocks and climate. — On page 257 we read: 'Prevailing red 

 color of the rock strata may also indicate comparative aridity.' This 

 statement is a surprise to me, as I thought I had shown in Bulletin 

 number 52, U. S. Geological Survey, and it has been conceded by sev- 

 eral subsequent writers, that rock waste in regions having a warm cli- 

 mate is characterized by its red color — as, for example, the red residual 

 soils of the southern Appalachian region, the terra rossa of southeastern 

 Europe, etcetera — while the rock waste of regions having a warm, arid 

 climate is characterized by a prevailing yellowish tone merging into 

 gray — as, for example, in the arid region of the United States." 



[The color of marine sediments and that of atmospheric rock waste are two 

 quite different problems. The shales and sandstones of saliferous periods— for 

 example, the Medina, Salina, Permian, and Trias— are characterized by red color.— 

 H. L. F.] 



"Corrugated mountains. — In speaking of the inadequacy of the con- 

 traction of the earth due to loss of heat, under the nebular hypothesis, 

 to account for the formations of mountains of the Appalachian type, the 

 essay before us fails to take account of another principle that must be 

 conceded to have been in operation at the same time and to have influ- 

 enced the corrugation of the earth's crust in a like manner. The phe- 



