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



batholiths upward; what brings them to rest where they differentiate; 

 what starts their fractional parts on their renewed migrations toward the 

 upper world, where they finally crystallize, solidify, and send their emis- 

 sions outward. Is it isostatic readjustment? Is it slowing down of the 

 earth's rotation and readjustment in shape? Is it the upsetting of 

 equilibrium by some unusual combination of attractive forces from other 

 bodies in outer space? Is it shrinkage from loss of heat? Is it a vast 

 local breaking loose and escape of highly heated interior gases, the blow- 

 pipe theory of E. E. Daly? Is it radioactivity in some little-understood 

 manifestation, with local development of heat, or is it some tertium quid, 

 as the old-time philosophers used to call it, not a third something or 

 other, but a seventh something or other, which we have not yet thought 

 of? Do all the common causes mentioned or any combination of them 

 cover all our difficulties ? Probably not ; but some time in the future the 

 septimum quid will be found. 



Eeferences 



1. Lardxer Vaxuxem : Geology of the Third District. New York State Sur- 



vey, 1842, page 207. 



C. H. Smyth, Jr. : A third occurrence of peridotite in central New York. 

 American Journal of Science, April, 1892, pages 322-327. 



Alnoite containing an uncommon variety of melilite. American Journal 

 of Science, July, 1894, pages 54-65. 



Note on recently discovered dikes of alnoite at Manheim, New York. 

 American Journal of Science, October, 1896, pages 290-292. 



Weathering of alnoite at Manheim. Bulletin of the Geological Society of 

 America, volume 9, 1898, pages 257-268. 



2. Lardxer Vaxuxem : Geology of the Third District. New York State Sur- 



vey, 1842. page 109. 

 George H. Williams: On the serpentine (peridotite) occurring in the 



Onondaga salt group at Syracuse, New York. American Journal of 



Science, August, 18S7, pages 137-145. 

 Note on the eruptive origin of the Syracuse serpentine. Bulletin of the 



Geological Society of America, volume 1, 1890, pages 533-534. 



N. H. Dartox and J. F. Kemp: Newly discovered dike at Dewitt, near 

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 456-462. 



P. P. Schneider: New exposures of eruptive dikes in Syracuse, New 

 York, with petrography by C. H. Smyth. Jr. American Journal of 

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3. Lardxer Vanuxem : Geology of the Third District. New York State Sur- 



vey, 1842, page 169. 



