408 DESCRIPTION OF THE COUNTRY BORDERING 
the overlying trap-bed proceeds from both of them, as shown in the preceding 
section. 
On the northwest side of this dike a fault occurs, which brings up an exposure of 
quartzose porphyry, resembling in all respects the rock forming the Great Palisades, 
and also the metamorphosed porphyritic beds below Hat Point. Some of the beds, 
when struck with the hammer, ring like clinkstone. The slaty beds above it dip 
to the northwest, and are overlaid by greenstone, as shown in the section, without 
any appearance, however, of the metamorphosed columnar beds seen on the south- 
east side of the dike. The quartzose shales are traversed by a vein of calcite, seven 
feet in width, which crosses the river to the Canada shore, where it is contracted to 
four feet. Its course is northwest and southeast, across the line of strike. 
A mile and a half above this place, the river is crossed by a dike of fine-grained 
greenstone, bearing east and west, and causing a perpendicular fall of nineteen feet. 
Above this is a rapid, which descends eleven feet in fifty yards, making in all a fall 
of thirty feet. The whole exposure of rock, which is traversed by numerous thin 
veins of calcite, is thirty-four feet. 
About nine miles above the mouth of the river, there is a rapid, made by a ridge 
of slaty greenstone (No. 42), flanked by altered slates below, dnd a bed of green- 
stone above. This ridge is composed, in part, of red siliceous porphyry (No. 41). 
The hills, on both sides of the river, are between three and four hundred feet in 
height. The fall is eleven feet in forty yards, in a succession of little cascades. 
The rock exposure is shown in the following section : 
1. Quartzose porphyry. 2. Argillaceous slates. 3. Slaty greenstone. 4. Hornblendic rocks. 
After passing this fall, the ridges become more frequent, and rise between three 
and four hundred feet above the river-level, the high valleys between them bearing 
a heavy growth of timber, among which are many large poplars and white birch. 
On the tops of the ridges, red clay and marl beds occur. Beyond this, the slate- 
beds begin to thicken, exhibiting escarpments in the river-banks, from forty to fifty 
feet in height, and mounting up the slopes of the hills, until the overlying green- 
stone-bed is reached. Throughout all this distance the bedded rocks are traversed, 
at irregular intervals, by narrow dikes, similar in composition, and having the same 
bearings, as those seen on the lake-shore. 
Between the mouth of Arrow River and the Great Cascades, after ascending from 
the valley of the river, the country is rolling, and covered with very large poplar, 
spruce, and birch. The river in this distance presents a succession of rapids and 
small cascades, with short intervals of gentle current between them. 
The Great Cascades of Pigeon River are about one mile below the west end of 
Grand Portage, once the site of “ Fort Charlotte,” for many years the most impor- 
tant post of the “Northwest Fur Company.” The scenery at the Cascades presents 
the singular combination of wild grandeur and picturesque beauty, with an aspect 
