IOWA ACADEMY OP SCIENCES. 49 



1. Fire. — This stands foremost in prominence among the 

 discussions of the past.* It has no doubt been effective in 

 reducing or checking forests, yet it alone could scarcely have 

 been entirely responsible for our prairies. In the first place 

 we have no proof that fires were sufficiently widespread before 

 the advent of the white man to alone account for the extent of 

 the prairies. Moreover fire-swept groves are by no means 

 always reduced to prairie, but are often soon restored, if 

 indeed they do not remain practically uninjured, the destruc- 

 tion of the underbrush often probably being of advantage to 

 the trees. Nay, groves, even when exposed and of limited 

 extent, have been able to persistently check the advances of 

 prairie fires, f Higher, dry places have frequently suffered less 

 from fires than comparatively wet lowlands, but this may be in 

 part explained by the more scanty vegetation of the former. X 

 There are no remains of charred wood, such as we might 

 expect in case of widespread destruction of trees by this 

 means. § 



The unequal and interrupted distribution of trees along 

 streams is scarcely consistent with the view that the streams 

 exerted any considerable influence in checking vast conflagra- 

 tions, and can in fact, be better explained in another manner. 

 However, that fire exerted some influence in the formation of 

 prairies, goes without question. It destroyed seedlings, and 

 in some cases large trees. The location of many groves in the 

 state suggests protection against fires. Such are Coon grove, 

 in Winnebago county, which is nearly surrounded by swamps; 

 an ash' grove on an island in Iowa lake, in Osceola county, || 

 where all else is prairie, and numerous groves in protected, 

 damp places, especially along streams, in various parts of the 

 state. True, the distribution of many of these groves may be 



*See: Am. Jour. Sci. and Arts, Series I, Vol. I, pp. 332-3, 1818; Vol. II, p. 36, 1830; 

 Vol. XXIII, pp. 40-45, 1833; Series II, Vol. XLI. pp. 154 et seq., 1866; O. A. White in Am. 

 Nat., Vol. II, p. 152, 1868; Dr. G. M. Sternberg In Am. Nat., Vol. Ill, p. 162, 1869; J. A. 

 Allen in Am. Nat., Vol. Ill, p. 577, 1869; C. A. White, Geol. of Iowa, Vol. I, pp. 131-3, 1870; 

 C. A. White In Am. Nat., Vol. V, p. 68, 1871; T. H. Macbrlde in the following: Iowa Geol. 

 Sur., Vol. IV, p. 115, 1894; Proc. Iowa Acad. Scl., Vol. Ill, pp. 96-101, 1896; Iowa Geol, 

 Sur., Vol. IX, pp. 148-9, 1898; Iowa Geol. Sur., Vol. X, advance sheets, p. 4, 1899. 



tSee: A. Fendler in Am. Jour, of Sol. and Arts, Series II, Vol. XLI, pp. 154, et seq., 

 1866; T. H, Macbrlde in Proc. Iowa Acad. Sci., Vol. Ill, p. 97, 1896. 



*R. W. Wells in Am. Jour, of Sci. and Arts, Series I, Vol. I, p. 333; T. H. Macbrlde 

 In Proc. Iowa Acad. Sci., 1. c, and Iowa Geol. Sur., Vol. IX, pp. 148-9, 1898. 



§T. H. Macbrlde, Ibid. 



II Reported by T. H. Macbrlde. 



