176 Scientific Intelligence — Geology. 



region, smaller than the others, lies between the three great lakes — 

 Erie. Huron, and Michigan. Competent geologists affirm that, fro 

 a comparison of the coal strata of contiguous basins, these are no 

 more than detached parts of a once continuous deposit. 



The extent of this enormous coal field is, in length, from north- 

 east to south-west, more than 7^0 miles, and its greatest breadth 

 about 180 miles; its area, upon a moderate calculation, amounts to 

 63,000 square miles ! In addition to these, there are several de- 

 tached tracts of anthracite in Eastern Pennsylvania, which form some 

 of the most remarkable coal tracts in the world. They occupy an 

 area of about 200 square miles. 



The strata which constitute this vast deposit comprehend nearly 

 all the known varieties of coal, from the dryest and most compact 

 anthracite to the most fusible and combustible common coal. One 

 of the most remarkable features of these coal-seams is their prodi- 

 gious bulk. The great bed of Pittsburg, extending nearly the entire 

 length of the Monongahela River, has been traced through a great 

 elliptic area, of nearly 225 miles in its longest diameter, and of the 

 maximum breadth of about 100 miles, the superficial extent being 

 14,000 square miles, the thickness of the bed diminishing gradually 

 from 12 or 14 feet to 2 feet. In 1847 the anthracite coal regions 

 of Pennsylvania furnished 3,000,000 tons, and 11,439 vessels cleared 

 from Philadelphia in that year, loaded with the article. The produce 

 in 1848 and the present year, is of course larger. 



The bituminous coal area of the United States is 133,132 square 

 miles, or one 17th part of the whole. The bituminous coal area of 

 British America is 18,000 square miles, or one 45lh part; Great. 

 Britain, 8139 square miles; Spain, 3408 square miles, or one 52d 

 part ; France, 1719 square miles, or one 118th part ; and Belgium, 

 518 square miles, or one 122d part. The area of the Pennsylvania 

 anthracite coal formations is put down at 437 square miles ; and that 

 of Great Britain and Ireland anthracite and culm, at 3720 square 

 miles. The anthracite coal of Great Britain and Ireland, however, 

 is not nearly so valuable an article of fuel tis the anthracite coal of 

 Pennsylvania, nor does a given area yield so much as the latter. — 

 New York Express, American Annual of Scientific Discovery^ 

 p. 271. 



8. River Terraces of the Connecticut Valley. — At the meeting 

 of the American Association in August, President Hitchcock of 

 Amherst College, read a paper " On the Biver Terraces of the Con- 

 necticut Valley, and on the Erosions of the Earth's Surface." He 

 stated that his paper must be considered as containing a few facts 

 and suggestions and not a finished theory. He has examined the 

 valley from its mouth to Turner's Falls, and carefully measured the 

 heights of the terraces. " As you approach the river you find plains 

 of sand, gravel, or loam, terminated by a slope sometimes as steep 

 as 35°, and a second plain, then another slope and another plain, 



