Gregory] VOLCANIC TUFF. 121 
All these tuffs are waterlaid and show an assortment of the coarser 
and liner materials into a rude stratification, as the rock is seen in the 
ledge, and loose bowlders from apparently the same outcrops show 
their bedding distinctly. Cleavage planes running toward the north- 
east cut the ash beds, and small faults and slickensided surfaces are 
commonly present. The embedded pebbles show results of strain, and 
occasionally are so cleaved and fractured that they drop into angular 
fragments when removed from their matrix. 
Silicified type. — An exposure of a hard, black silicified tuff was 
found on the brow of a steep hill about one-eighth of a mile east of 
the mouth of Welts Brook. The rock is broken into huge cubes by 
cleavages in the ledge, and loose blocks are strewn over the slope. 
The density of the forest growth and the thick mat of vegetable debris 
prevented a detailed study of the structural relations of this outcrop. 
The relation of these volcanic ash beds to the other rocks of this 
vicinity was not made out with certainty, on account of the small num- 
ber of outcrops and the absence of exposed contacts. So far as worked 
out, however, the facts indicate that the tuffs are contemporaneous 
with the andesitic flows. The normal type of ash, the cm structure, 
and the andesitic lava and breccia all have their best development 
within a radius of a few hundred feet, and are believed to be near the 
original vent. The nearest sedimentaries are about an eighth of a mile 
distant on the east and somewhat nearer on the west, and wherever 
seen are clearly folded and occasionally baked. The present ash beds 
are considered as remnants of somewhat more extended beds which 
were laid down upon folded calcareous and arenaceous slates through 
which the volcanic vent had been drilled. 
TUFF IN NORTHEAST PART OF ASH LAND TOWNSHIP. 
The outcrop of volcanic tuff in this locality is on the north side of 
the lower Presque Isle-Ashland road, about 2i miles west of Haystack 
Mountain, and is made up of ash in beds of differing aspect, together 
with an intrusion or flow of andesitic character. Part of the tuff 
appears in the field as porcelainlike material, while the most typical 
ashy variety presents surface characters much like coarse amygdaloidal 
lava, for which it has been mistaken. 
TUFF ON THE ASHLAND-SHERIDAN ROAD. 
The volcanic tuff exposed in the road near the boundary line between 
Ashland and Sheridan townships is merely the most tuffaceous member 
of a number of outcrops which are all more or less pyroclastic in their 
composition and which are found along the road and in the river in 
this neighborhood. In speaking of this locality Hitchcock 1 notes the 
1 Agriculture and Geology <>t' Maine, 1861, p. 391. 
