26 I. C. RUSSELL CONCENTRATION AS A GEOLOGICAL PRINCIPLE 



the deposit of carbon in question- — that is, the fact that accumulations 

 of material must be present or their conservation insured for, in general, 

 a great length of time in order to be of geological or economic impor- 

 tance. Methods of preservation thus become only secondary in importance 

 to the methods of primary concentration. In the case of carbon, accumu- 

 lations are made; this concentration is promoted in several ways, promi- 

 nent among which is submergence in water, which, as a part of the 

 process, is rendered to a conspicuous degree antiseptic by reason of certain 

 products of organic origin, as is well known in the case of the amber- 

 colored water of swamps; still longer preservation is involved when 

 peat-bog, drift timber, etcetera, become buried beneath sediment or 

 other deposits, which serve to compress it as well as exclude the ravenous 

 oxygen. Another important method of preservation, and one to which 

 but little heed has been given, is illustrated in the vast tundras of another 

 latitude, where vegetable matter comparable in volume with that of our 

 largest coal fields has it decay arrested by low temperature. The incipient 

 coal beds of the tundra marshes owe their preservation literally to a 

 process of cold storage. In the review that is evidently demanded of 

 the glacial records of approximately Permian age in various parts of 

 the world, the suggestion that some of the late Paleozoic coal beds are 

 of tundra origin may, perhaps, make certain facts significant which 

 would otherwise be passed by with scant attention. 



CALCIUM CARBONATE 



The methods of concentration through the action of plants, of calcium 

 in combination with carbon dioxide, recently so clearly demonstrated by 

 Weed in reference to hot-spring deposits, and by Davis concerning the 

 so-called marl of freshwater lakes, are of fundamental importance to 

 geologists. If such striking results are now produced by this method 

 of concentration, our cherished faith in uniformatism should certainly 

 lead us to scan the history of past times with the hope of learning when 

 this function began to be exercised and what part it has played in record- 

 ing geological events. The question is pertinent. Do the more or less 

 local and frequent lenticular beds of limestone in certain formations now 

 partly crystalline schists, represent the products of concentration brought 

 about by algge? 



Other and more familiar methods by which the concentration of cal- 

 cium carbonate is brought about need only be mentioned to indicate 

 the important place they hold in the scheme of classification of the widely 

 extended operations of nature under review, which in truth have made the 

 earth habitable by living creatures. The hard parts of foraminifera, 



