336 The American Geologist. December, i898 
of the Casco bay, and the southern portion of the Freeport 
quadrangle of the United States Geological Survey. 
Tile fjord-like character of the bay with excessively in- 
dented coast-line, and the efifects of glaciation on the islands 
are well brought out on the map. 
The trend of the islands is northeast, and corresponds with 
the strike of the crystalline schists composing them. These 
schists are, according to Hitchcock,* of Huronian age, and 
extend from near Saco river to Harpswell, abutting against 
gneiss (Laurentian) on the east, and are overlain to the west 
and northwest by strata of Cambrian age.t They consist of 
finely stratified micaceous quartzytes, biotite, chlorite, and 
actinolite schists, merging locally into garnetiferous and staur- 
olitic varieties. These strata are undoubtedly of clastic ori- 
gin, but their original structure is in many cases almost totally 
destroyed by the far reaching effects of a regional metamor- 
phism. They have a remarkably regular N. 50° — 60° E. 
strike, and are generally inclined at high angles to the north 
or south. Cleavage is especially well developed in the fine 
grained micaceous schists forming the greater part of the 
series. On weathered surfaces this rock bears frequently 
cjuite a striking resemblance to irregularities of surface of de- 
caying, coarse-grained timber, and breaks up locally in long 
thin layers, not unlike fence rails. A slab, showing this pecu- 
liar form of weathering, is figured in "Rocks, Rock-weather- 
ing and Soils," by Prof. G. P. Merrill, MacMillan & Com- 
pany, 1897. In describing it (page 248) the author says: 
"The finely fissile schists, standing nearly on edge along 
the coast of Casco bay, in Maine, under the combined in- 
fluence of wave and atmospheric action, weather into peculiar 
fantastic forms resembling nothing more than piles of lumber 
in which multitudinous channels formed by boring coleopter- 
ous larvae have become irregularly enlarged by decay." 
Apart from secondary folding and some local shearing and 
faulting the schists show evidence of considerable jointing sub- 
sequent to the intrusion of the dikes. The jointing afTects the 
*Chas. H. Hitchcock: The Geology of Portland, Me. Proc. Amer. 
Assoc. Adv. Sci., Vol. XXII., 1884, p. 164. 
tSee geological map of Maine. C. H. Hitchcock: Geology of 
Northern New England, 1885, p. 5. 
