5 20 THE POPULAR SCIENCE MONTHLY 



of coniferous trees ; while some of the trees peculiar to the valleys 

 west of the Alleghanies grow on the Silurian and Devonian beds. 



The Appalachian province is composed of all the geological forma- 

 tions of North America, and its regions are very distinct. 



The Alleghany region, comprising the eastern slopes of the up- 

 lands, and the lower Alleghanies, terminating in a point of latitude 34 

 in Georgia, is mostly granitic, but has streaks of Silurian and Triassic 

 running through it. We find the same class of trees in it that grow 

 in the Canadian region (Canada), with a few added which are perhaps 

 limited by heat. These, with a few oaks and hickories, which are more 

 prevalent on the Triassic formation than elsewhere, form the bulk of 

 the forest-growth. 



The Ohio region, embracing the eastern uplands of the Ohio Valley, 

 east of the prairies and north of latitude 38, is conrposed geologically 

 almost wholly of Silurian, Devonian, and carboniferous beds, covered 

 in places with drift from the north. It is marked by its large number 

 of deciduous trees, no other country boasting of so many fine oaks, 

 hickories, and walnuts. It is, however, very poor in conif era?, and, but 

 for a few stragglers, might be said to have none. Allied species are 

 found to be plentiful in the tertiary formation nearly across the conti- 

 nent, indicating that this class of trees at one time reached from the 

 Alleghanies to the Rocky Mountains, the middle of the belt having been 

 destroyed by the more recent changes of the physical conditions of the 

 earth's surface. As they have never returned since the glacial epoch, 

 the inference is that the conditions of soil and climate have been so 

 changed that the country west of the ninety-seventh degree of longi- 

 tude is not capable of supporting these trees. 



The Tennesseean region is a southwestern continuation of the 

 Ohio region. It is composed of the same geological beds, with a few 

 spurs of the granite ridges of the Alleghanies running into it, and 

 therefore contains more conifera? than the Ohio region. Still, the 

 bulk of its timber is of the same class of broad-leaved trees that are 

 found north of it, the only differences being such as climate alone 

 makes. 



The Carolinian region borders on the Atlantic coast between the 

 Alleghany Mountains and the ocean from Middle Georgia to Long 

 Island. It is composed of cretaceous and tertiary beds, with a strip 

 of Triassic along the western edge. In the northern portion are some 

 beds of drift of granite from the north. Here we have a distinct class 

 of conif era? on the cretaceous beds that are peculiar to this region, 

 and another class on the drift that are also found growing farther 

 north. Arthur Ilollick,* who has made observations on the flora of 

 Staten Island, says : " We have on Staten Island two well-marked 

 geological formations : the drift, which covers about two thirds of the 

 entire island, nearly all of the northern part, and extending as far 



* " Bulletin of the Torrey Botanical Club," vol. vii, p. 14. 



