1846.] Geological Survey of Canada. 53 



bottom of the lowest sedimentary formation, with a transverse 

 axis, reaching from Michigan to the neighborhood of Washing- 

 ton, a distance of seven hundred miles; and a longitudinal one 

 extending from Quebec in a south westerly direction to the Ten- 

 nessee river in Alabama. In this great trough are three subordi- 

 nates, in the centre of which, there spreads an enormous coal 

 field. One commencing on the southern borders of Kentucky and 

 extending north westerly to Rock river, in Illinois, is 360 miles 

 long, and in breadth 200. It is of an oval form, and is intersect- 

 ed by the river Illinois, Wabash and Ohio. It is bounded by the 

 Mississippi, which sweeps along nearly the whole western margin. 

 It covers an area of 55,000 square miles. The second coal field, 

 the heart of Michigan, extending one hundred miles east and 

 west, and one hundred and fifty miles north and south ; commenc- 

 ing: from the neio^hborhood of the rivers Manistee and Ausable 

 and terminating at the source of the Grand river near Jackson. 

 It has a superfices of 12,000 square miles. The third carbonifer- 

 ous area stretches in a north-easterly course about 600 miles, be- 

 ginning in the State of Tennessee and extending to the north 

 corner of Pennsylvania. Measured transversely, or from the north 

 branch of the Potomac, in Maryland, to the south-eastern corner 

 of Summit county in Ohio, it is 170 miles. Its form is some- 

 what rhomboidal, and is supposed to comprise an area of 60,000 

 square miles. It is traversed by the Ohio and Susquehanna; the 

 main trunk of the former passes through its centre, or traverse it 

 for about 400 miles. The latter intersects with its tributaries, 

 the north-eastern extremity, and denudes and lays bare the series 

 of rocks down to the New-York system beneath, and which of 

 course are exposed in their outcrops. 



The most important part of Mr. Logan's report is the Append- 

 ix, which constitutes nearly one half of the pamphlet. It com- 

 prises a detailed examination of the Nova Scotia coal measures 

 as developed at Joggins, on the Bay of Fundy. The whole 

 formation has been reduced to vertical thickness, and every sub- 

 ordinate mass measured and described. 



The formation consists of sandstone, gray, brown or drab, and 



