58 



NEW YORK STATE MUSEUM 



become a coaly black glass from the effects of chill, and always the 

 borders are denser than the centers. One very interesting case has 



xoft 



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Fig. 9 Step-faulted dike in Walker brook, North Hudson 



been found of one dike penetrating another and chilled by it. 

 There were clearly two periods of intrusion in this instance and 



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30 



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Fig. 



ro Basaltic dike in an irregular and jagged crack on Slide brook. The dike strikes 

 15° e. and dlp.s io° east. The wall rock is gabbro of the Solit Rock Falls typa. vj| 



