A SECOND CONTRIBUTION TO THE NATURAL 

 HISTORY OF MARL^ 



The writer recently published a paper on the relation of 

 algae to marl deposits.^ Since it appeared, continued investiga- 

 tion has led to the discovery of additional confirmatory evidence 

 that the close relationship there pointed out of the algae, espe- 

 cially Chara, to marl or lake lime deposits, exists to even a 

 greater extent than was suspected. 



Experimental work has been conducted along three lines, all 

 of which have been fairly productive of results, and a brief 

 account of this work may be of interest. 



First, a series of mechanical analyses of typical white marl 

 from different localities were made. The method of analysis 

 used was a simple one, a modification of the beaker method 

 used in soil analysis. The sample, chosen at random from a 

 large specimen from the deposit under investigation, was dried 

 in an air bath at i io° C. for sufficient time to remove any included 

 moisture, and weighed. It was then mixed with distilled water 

 in a large beaker and thoroughly stirred with a rubber-tipped 

 glass rod, care being taken to stir it until all lumps caused by the 

 adhesion of the finer particles to the coarser were broken up 

 Care was also taken that no more crushing should take place 

 than was absolutely necessary. After all lumps were disinte- 

 grated, the water, with the finer particles suspended in it, was 

 poured off into another beaker and fresh water was added to 

 the first and the material was again stirred. This was continued 

 until water poured into the first beaker was nearly free from 

 finer matter and became clear on standing a few moments. The 

 coarse material left in the bottom of the beaker was dried, sorted 

 into various grades by a series of sieves and each grade weighed. 



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

 ^'JOUR. Geol., Vol. VIII, No. 6. September-October 1900. 



491 



