304 C. !;. KEYES — MARYLAND GRANITES AND THEIR ORIGIN. 



These proofs of eruptive origin of the Maryland granites are quite 

 similar to those which Barrois* has formulated from the granites of 

 Rostrenen. 



d. Microscopic Examinations. — Aside from the ordinary microscopic 

 characters indicative of cooling from fusion, certain of the granites under 

 consideration show some additional phenomena pointing to the same 

 end. These are Large grains, micropegmatitic Lntergrowths of quartz and 

 feldspar, rounded through magnatic corrosion apparently and having 

 the characteristic embayments so commonly associated with cases of 

 this kind. 



*Ann. de la Soe. geol. du Nord, t. xii, p. 106, 1885. 



