A CONTRIBUTION TO THE GEOLOGY OF SOUTHERN MAINE 535 



I. Analysis, molecular proportions and norm of sitlcose from Fisher- 

 man's Island, Me. 

 II. Analysis, molecular proportions and norm of sitkose from Alaska, 

 described by Becker; analysis, by Hillebrand. Analysis and norm 

 published in Washington's tables, Prof. Paper 14, U. S. G. S. 

 p. 219. (.61% of rare. oxides omitted.) 



The Maine rock is perfectly fresh, as regards weathering; the 

 Alaska one contains notable amounts of water and of carbon 

 dioxide and is described as containing secondary chlorite, calcite 

 and muscovite. The comparison between them cannot there- 

 fore be pushed too far. It is well known that in the weathering 

 process the lime is the first constituent to be attacked and that 

 of all the others alumina is the most constant actually, but 

 apparently grows greater because of the percentage decrease in 

 the others. These two analyses would be much closer if a 

 recasting were made because of weathering. 



Norm and Mode. — In the less crushed varieties of the Maine 

 rock the mode differs from the norm mainty in the entire absence 

 of anorthite and the presence of various calciferous alferric 

 minerals. Titanite is moderately abundant, thus using up the 

 ilmenite molecule in combination with CaO. There is a very 

 little biotite, which calls for a slight re- arrangement of the potash 

 molecules. 



Metamorphism. — As a rule the rock has been greatly sheared. 

 The shearing took place in some instances along the strike of 

 the dike, in some directly across it, and in some obliquely. The 

 result of the shearing is seen in granulation of the quartz, un- 

 dulatory extinction of quartz and feldspars, bending of the 

 feldspar lamella?, cracking of the feldspars and the pres- 

 ence of the metam orphic minerals microcline, actinolite and 

 zoisite. 



Grano-tonalose. II. 4. 3. 4. (Quartz-mica Diorite). Occur- 

 rence. — The rock which falls into this subrang makes up the 

 greater part of the island of Southport, where it is found in 

 irregular masses of bathylithic or laccolithic character. The 

 same type of rock occurs to some extent in the form of dikes on 

 the mainland. 



Megascopic Character. — It is a fairly coarse-grained light gray 

 rock of granitic texture occasionally gneissoid. In the field it 



