234 J. F. KEMP AFTER-EFFECTS OF IGNEOUS INTRUSION 



by just so much as we attribute to an intrusive dike the power to coke 

 tightly confined and compressed lignite ; but the more one reflects on the 

 matter, the more one is inclined to allow a goodly stretch of geologic 

 time. Will the Permian suffice, so that the dikes were coincident with 

 Appalachian upheavals? Are the parent magmas more western relatives 

 of the post-Carboniferous granites of Ehode Island and Connecticut? 

 Are they western representatives of the magmas which yielded the ex- 

 tensive late or post-Jurassic diabases of the Atlantic coastal region ? Are 

 they in any way related to the intrusives of Cretaceous age, which are 

 best developed in the syenite magmas of Arkansas? These are questions 

 more easy to ask than to answer ; but one can not avoid reflecting on the 

 powerful heat agents which may have affected, since the close of the 

 Carboniferous, the lower strata in the localities mentioned. 



Again one might cite the flat beds of the Coastal Plain around the 

 Gulf of Mexico, joenetrated, as they are, by basaltic plugs and stocks near 

 Tampico, 7 and raise the question as to the parent reservoirs and their 

 depths. Even in Texas and Louisiana our reasoning about the salt domes 

 and their attendant sulphur-bearing caps of limestone and anhydrite 

 seems unable to bar out altogether subterranean intrusive masses. Last 

 winter, at the Chicago meeting of the Society, when we heard the inter- 

 esting paper of Dr. W. IT. Bucher, 8 in which he described the centrally 

 eroded and steeply, outwardly dipping dome in Adams County, on the 

 Ohio River, in Ohio, and the parallel drawn by the author with similar 

 phenomena near Steinheim, Wurtemberg, we could not help contemplat- 

 ing the possibility that beneath this upheaval a laccolith might lie con- 

 cealed. I repeat, that we are never safe from igneous rocks, at no vast 

 depths, no matter how innocent flat strata look at the surface. 



MlNERALIZERS REMAINING IN CRYSTALLIZED IGNEOUS ROCKS 



Observation and interpretation have now built up a widespread and 

 generally accepted conception of the process of crystallization in an in- 

 trusive mass which has practically finished its upward journey from the 

 depths. In great detail and in such grades of accuracy as we may readily 

 judge under the guidance of our fellow-member, Henry S. Washington, 9 

 our well-nigh innumerable analyses show us what are the chemical com- 

 positions of the chilled and cold results of crystallization. But we all 

 know that these are but a part of the story. All magmas contain dis- 

 solved gases which we technically call mineralizers. Traces of them re- 

 main even in cold, hard, crystallized end-products, and regarding the 

 composition and amounts of the traces we have the valuable paper of 



