J 80 Dr. BiGSBY on the Geographi/ and Geology of Lake Huron. 



the well-grown timber (still leaving- some uncommonly large hemlock), and 

 have exposed the ascending sides of the island in many places. The shores 

 are loaded with successive banks or stairs of small debris, and have here and 

 there terraces of limestone in situ. Mounting upwards, the ground is rugged 

 with protruding strata and rolled primitive masses ; and not unfrequently in- 

 tersected by short ledges, which often crown the greatest heights, affording a 

 table-land of small extent, and better wooded than the surface below, which is 

 only sprinkled with very young poplar-, birch-, and cherry-trees. 



There is a convenient harbour on the north side in the second bay from the 

 Third Detour. It is a deep oblong indentation in this bay, and itself contains 

 an inner cove. It is a quarter of a mile broad. The ship entrance is narrowed 

 to a few yards by a shoal that runs from the east angle two-thirds across. 



Within this bar a vessel may ride with from 9 to 12 feet water in tolerably 

 roomy anchorage, the depth decreasing gradually towards the bottom of the 

 indentation. 



The third detour, between Little and Grand Manitou, is 8 miles long by 4 

 broad, with high shores, and clear at both outlets. Off the south-east end of 

 the Little Manitou is a very extensive but easily distinguished shoal. 



The Grand Manitou may be estimated at 75 miles long, and 8 miles broad 

 on the average. About its middle it is 25 miles broad, and at two places to 

 the west of the widest part, the shores are so deeply indented as nearly to 

 divide the island, only narrow morasses intervening between opposite bays. 



The general characters of the Grand Manitou are the same as those of 

 Drummond, but on a larger scale. It is higher, abounds more in precipices, 

 and is more rugged throughout*. At the western end it is of more majestic 

 features than any of the country which I have seen in other parts of Lake 

 Huron. At the north end of the Third Detour, its shores are lined with 

 ranges of shingle, supported behind by an ascending country of woods. — 

 Toward the centre of this strait, ledges and low precipices begin to appear 

 along the beach, and soon rise to the height of 250 feet, crowned with cedar 

 and pine. These ledges either rise perpendicularly, or are formed of enor- 

 mous piles of displaced masses, from 7 to 10 yards in diameter, sloping at a 

 high angle. These blocks advance into the water, and afford a hazardous 

 path over their slippery sides, under arches and through winding passages. 

 Within half a mile of the south-east angle of the Detour, a bluff precipice 

 40 feet high protrudes into the water, skirted by very large cubic masses of 

 rock. Of such masses, resting precisely on one another, the bluff itself is 



* The above particulars I learnt from my friend and companionj Lieut. John Grant, R.N.j 

 having myself only visited the western end of the island. 



