A CONTRIBUTION TO THE NATURAL HISTORY OF 



MARL. 1 



Botanists have long been familiar with the fact that, in some 

 regions, aquatic plants of all, or nearly all, types are covered 

 with a more or less copious coating of mineral matter, while in 

 other localities the same types of plant life are free from any 

 trace of such covering. In New England, for example, plants 

 growing in the water are generally without such coating, while 

 in Michigan and adjoining states it is generally present. In 

 many lakes and streams the mineral deposit on the stems and 

 leaves of the higher plants is very noticeable, and nearly all 

 vegetation growing in the water is manifestly an agent of pre- 

 cipitation of mineral matter. 



Various writers in Europe 2 and America 3 have called atten- 

 tion to the influence of the low types of plants growing in and 

 around hot springs and mineral springs, on the formation of 

 silicious sinter, calcareous tufa, and other characteristic deposits 

 of such springs, and the connection between the beds of cal- 

 careous tufa which are sometimes formed about ordinary seepage 

 springs whose waters carry considerable calcareous matter in 

 solution and certain species of moss has been suggested, but so 

 far as the writer knows, no one has given attention to the possi- 

 ble relation of vegetation to the more or less extensive beds of 

 the so-called marl, found about, and in, many of the small lakes 

 in Michigan and the adjacent states. As has been pointed out 

 elsewhere, "Marl" is made up principally of nearly pure cal- 

 cium carbonate, "carbonate of lime," with greater or less 

 admixture of impurities. When dry and pure, it is white or 



1 Printed by permission of Alfred C. Lane, State Geologist of Michigan. 



2 Cohn: Die Algen des Karlsbader Sprudels, mit Riicksicht auf die Bildung des 

 Sprudel Sinters : Abhandl. der Schles. Gesell., pt. 2, Nat., 1862, p. 35. 



3 Weed : Formation of Travertine and Silicious Sinter by the Vegetation of Hot 

 Springs. U. S. Geol. Surv., IX, Ann. Rept., p. 619, 1889. 



*8q 



