398 



DESCRIPTION 



0 F T H E 



PENINSULA 



local disturbance, where they cut up through the slates, tilting them, occasionally, 

 entirely on end. 



These dikes are, usually, coarsely crystalline in the centre, but finer-grained near 

 their junction with the slate, probably in consequence of cooling more rapidly and 

 of being subjected to pressure from the adjoining slates. The slates, near their 

 contact with the dikes, exhibit evidence of having been exposed to great heat, and 

 occasionally even resemble, in texture, the volcanic dikes themselves; resuming 

 however, gradually, their natural structure as the distance increases. 



The dikes, sometimes, are composed of irregularly pentagonal and hexagonal 

 columns, lying at right angles to the line of upheaval, at right angles, consequently, 

 also, to the lateral cooling surfaces. 



The accompanying map and section* (in which the height of the slates is, neces- 

 sarily, exaggerated, to give a good idea of the general dip and local disturbances), 

 will probably serve to convey some idea of these grand convulsions of Nature, 

 which, however, as you are well aware, have to be seen in order to be appreciated. 



The more minute details, beginning at the mouth of Pigeon River, and finishing 

 at the Grand Portage, are given in the following " Notes from my Journal." 



As it rained during the night, although we rose at 3h. 30m. A. M., we did not set 

 out until 6h. 10m. The first point of importance, after leaving the mouth of Pigeon 

 River, and following the coast in an easterly direction, is a dike of massive green- 

 stone (No. 654). In the rear of this, when viewed from the Lake, a trap ridge is 

 seen, about one hundred and fifty feet high, chiefly covered with birch and moun- 

 tain ash. 



About half a mile from the mouth, a basaltic-looking rock (No. 656), probably a 

 metamorphosed clay slate, appears, from ten to fifteen feet high (the distances being 

 estimated from the lake-level), with a vein of calcareous spar in the slate eighteen 

 inches wide, besides two smaller veins ; then bluff rocks, fifty feet high, of trap, with 

 a north-and-south vein containing a gangue of argillaceous material (No. 657), and 

 sulphate of baryta in its centre. The bluff terminates east in a trap dike, with 

 shale (No. 658). The slate continues for a considerable distance, varying in height 

 from five to twenty feet. 



At the next point of note, we find fine-grained basaltic trap (Nos. 659 and 660), 

 succeeded by trap, in bluffs twenty to twenty-five feet high, rising finally to one 

 hundred and fifty feet. 



These bluffs are, probably, lateral spurs from the backbone ridge ; they occur at 

 a distance estimated as somewhat more than a mile from the mouth, and the loca- 

 lity may be recognised by having, in large letters, the word ENINI scratched upon 

 the rock, probably by some of the Grand Portage band of Indians, who, under the 

 care of Catholic missionaries, have made considerable progress in reading their own 

 language, printed in Roman characters. 



The wind blowing too hard for the canoe, we had to put back some time ; and 

 when we again started, at 8h. 30m., a. m., and reached the same point, we soon ob- 

 served another trap dike and overlying trap, one hundred and fifty feet high, run- 



* See PI. N. 



