Lake Maxinkuckee, Physical and Biological Survey 47 



Sample No. 1, from a bar east of the Long Point bar, just 

 south of the center of the northeast quarter of Section 28 : 



Calcium carbonate (CaCO 3 ) 85.02 



Magnesium carbonate (MgCOs) 3.85 



Ferric oxide (Fe 2 3 ) 0.33 



Alumina (A1 2 O 3 ) 0.12 



Calcium sulphate (CaSCX) 0.17 



Insoluble inorganic matter (silica, etc.) 5.67 



Organic matter 3.21 



98.37 



Sample No. 2, taken 5 feet down in a bed in 8-foot water 



Calcium carbonate (CaCO s ) 85.38 



Magnesium carbonate (MgCO 3 ) 3.50 



Ferric oxide (Fe 2 O 3 ) 0.33 



Alumina ( A1 2 O 3 ) . 05 



Calcium sulphate (CaSO 4 ) . 17 



Insoluble inorganic matter (silica, etc.) 6.40 



Organic matter 3 . 15 



98.98 



Sample No. 3, from the surface of a marl bed in deep water 

 off the Gravelpit : 



Calcium carbonate (CaCO 3 ) 75.07 



Magnesium carbonate (MgCOs) 4 . 18 



Ferric oxide (Fe 2 3 ) 0.51 



Alumina ( A1 2 O 3 ) . 09 



Calcium sulphate (CaS0 4 ) 0.11 



Insoluble inorganic matter (silica, etc.) 15.26 



Organic matter 3 . 65 



98.87 



The last of these shows too high a percentage of magnesium 

 carbonate and insoluble elements to render it satisfactory in 

 cement making. The first and second samples are much purer, 

 and would make a good cement. 



The origin of marl is a question of popular interest. The marl 

 of Lake Maxinkuckee, as well as of the other lakes of northern 

 Indiana, is evidently a secondary deposit on the original bed of 

 glacial drift. The water of all the wells and springs of the region 

 contains more or less lime and is usually regarded as hard, while 

 the water of the lake, although containing considerable calcium 

 carbonate, is relatively soft. That certain species of animals and 

 plants dwelling in the lake have been important, perhaps the only 



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