MUSEUM OF COMrAPvATlVE ZOlJLOGY. 69 



have occurred in the rock since eruption, as sliown by microscopic exam- 

 ination, may also help. It is well known that there are facts in every 

 science that it is not able to explain at any one given time ; but the 

 facts exist the same, and the science in time rises to meet them. So in 

 this case the fact is they are eruptive, and the burden of chemical ex- 

 planation rests upon the chemist, not upon us. He must explain it 

 sooner or later, unless he disi)roves our observations. Crystals of hema- 

 tite crystallizing from the molten magma of trachytes and rhyolites 

 have long been known, and are described in all the standard works 

 on micro-lithology. These then offer the same problem, and prove that 

 hematite can be crystallized directly out of the same molten magma, 

 and at the same time with the silica and silicates. It is the business of 

 the chemist to meet the fjxcts, and not for us to make the facts con- 

 form to his knowledge or theories. It is our business to state what we 

 see and find, and his to explain it if he can, but not to deny it for the 

 simple and sole reason that he cannot cope with it in the present state 

 of his knowledge. The eruptive origin of the iron also has a bearing on 

 the theory that its presence indicated a vast amount of organic life in 

 the " Huronian '' epoch. 



We have found that a large proportion of the rocks said to be inter- 

 stratified, and to pass by insensible (or any other) transitions into the 

 adjacent rocks, are eruptive, and do not so pass into the country rock. 

 The assumption that they were stratified was based on their foliation 

 being parallel to their walls, on their being intrusive approximately par- 

 allel to the lamination of the schists, their general resemblance to the 

 country rock of similar chemical composition, the inability of the observ- 

 ers to find their lines of junction, and the lack of knowledge of the same 

 observers of the characters of eruptive as well as of sedimentary rocks. 

 Their decision in this, as before, was based on a mere superficial glance 

 over the surface, and the assumption that, because a rock looked as 

 though it was stratified, i. e. had any marks that they thought indicated 

 stratification, it must of necessity be stratified. No effort was made to 

 find out the real relations of the rocks to one another. No attempt 

 was made to see whether one rock was laid down on another as a sedi- 

 mentar\' bed, or whether it was an overflow or intrusion. They were 

 *' striped " or foliated, jointed or showed cleavage planes, and that was 

 enough ; any further observation was superfluous. They assumed that 

 Messrs. Foster and Whitney's work was erroneous without making the 

 necessary observations to prove it so, and the geological world accepted 

 it without question because it agreed with the fashionable theories. 



