MASSACHUSETTS PEAT L.\NDS 39 



since it may be regarded as probable that a considerably larger 

 number of days with a water vapor blanket reducing low tempera- 

 ture in the critical frosty days of the growing period may result 

 from the enhanced evaporation conditions consequent to the 

 increase in cultivation. This may make the relative humidity 

 conditions and therefore the duration of the growing period for 

 crops more advantageous in certain localities with peat lands of 

 greater depth of materials. But this question and others connected 

 more chiefly with physiological effects of field conditions on crop 

 plants demand a more thorough study than has been at present 

 accorded to peat investigations. 



III. The geological and topographic factors. ' 



Owing to the solvent action of disintegrating masses of vegetable 

 material a consideration of the underlying rocks and soils has 

 therefore great importance practically as well as theoretically, 

 because they are in many respects the causes of the more primary 

 differences between marly alkaline to neutral peat lands and ferru- 

 ginous and acid peat lands ; they determine also in a great measure 

 the degree of disintegration, leaching, and weathering of peat, and 

 they condition the particular drainage measure, the choice of the 

 crop system, and the cultural methods best suited to their respec- 

 tive peat materials. 



According to the relief of the land Massachusetts may be divided 

 into a number of physiographic provinces, each marked by its own 

 characteristic topography and geologic belts. 



In the western section of the state are the series of mountainous 

 ridges of rugged topography, the rocks of which consist of strongly 

 folded and faulted quartzites, limestones, slates, schists, etc., 

 mostly of Paleozoic age. Of primary consideration is the fact that 

 in the Berkshire Valley the peat lands of morainal lacustrine and 

 of valley topography are generally underlaid by marl and similar 

 calcareous substances. 



The Connecticut Valley is marked in general by the presence of 

 soft reddish Triassic sandstones and shales, with an occasional 

 trap ridge. East of it in the highlands occurs a belt of folded 

 sedimentary and metamorphic rocks and further eastward, grad- 

 ually sloping toward the coast, is a broad crystalline belt consisting 

 largely of metamorphic and igneous rocks, such as granites, mi- 



