144 CONTRIBUTIONS TO THE GEOLOGY OF MAINE. [bull. 165. 
Near the bridge at Smyrna Mills the slates in general are steel-blue 
in color, and so fissile that they split into flakes as thin as paper. The 
slating is very regular in a plane which strikes N. 70° W. , with a dip 
N. < 80°. Another plane of cleavage runs N. 40° E. and cuts the 
slates into large blocks. Interbedded with slates are thicker black clay 
layers and thin beds of micaceous sandstone. In two cases the sandy 
beds are replaced by coarse indurated conglomerate containing large 
rounded fragments of quartz, black slate, and fine grits. Only rarely 
do these coarse layers extend for any distance, but are commonly 
pinched out between the other beds. 
Along the track to the north of Smyrna Mills the slates are found 
to be much crumpled and distorted, and vary in color from green to 
gray, with occasional reddish layers. They all have a smooth surface, 
especially the green varieties, and the sandier layers are not promi- 
nent. In a cut south of milepost 117 are black slates with the steel- 
blue variety, having their bedding planes marked by a thick sprinkling 
of brilliant crystals of iron pyrites. The beds at this place strike 
N. 80° E. , dip south at a high angle, and the cleavage runs east- west. 
At Weeksboro, near the station, the slates are light gray, with very 
soft and greasy feel. They are folded, faulted, and twisted to an 
extreme degree, and show many small slickensides. The cracks are 
now filled with quartz, which indicates the amount and character of 
the distortion. All bedding and regular slating are here destroyed, 
and the rock breaks up into chips and irregular slabs. 
Near St. Croix Station the slates approach more nearly the charac- 
ter of typical phyllites. They are here steel-blue in color, somewhat 
micaceous, and split regularly into very thin slabs which strike east- 
west and dip N. < 80°. Thin beds of fine sandstone occur with the 
slates. 
Northward from St. Croix the sandy layers become a more prominent 
member of the phyllite series, and at the Mill Seat on the St. Croix 
River the rocks are micaceous sandstones in beds 2 inches to 2 feet 
thick, interbedded with blue-black slates, which are very smooth and 
have a greasy feel. On weathering, all the rocks at this place assume 
a pure white appearance, like a smoothly finished plaster wall. The 
finer layers are largely composed of minute mica flakes. The beds 
strike N. 85° E. and dip N. < 80°. One slaty cleavage is parallel with 
the bedding, while another prominent cleavage runs N. 20° E. and 
dips E. < 70°, thus cutting the beds into rhombs. 
At the "foot of dead water" on the St. Croix, in T. 9, R. 5, the 
rocks exposed are gritty slates with indistinct bedding. In the rail- 
road cut at this locality the rocks show a number of broad folds with 
minute plications on the limbs, and the beds are stretched and pinched 
out in places. Embedded in these slates are two big bowlders of igne- 
ous rock to which the slates have adjusted themselves. It is thought 
