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physiography and climate. From a geographical standpoint 

 the state of Connecticut is naturally subdivided into three areas, 

 viz., an eastern and a western highland and a central lowland. 

 The boundaries of these divisions are roughly indicated on 

 the accompanying map (fig. 2). The highlands, underlain by 

 resistant granites, gneisses, and schists, contrast sharply with the 

 lowland where the bed rock is composed largely of soft shales and 

 sandstones. The contour of the highlands is for the most part 

 rugged, but it is in the northwestern section of the state, among 

 the southern Berkshires, that the greatest unevenness prevails. 

 Elevations of 450 meters are common here, while there are 

 several mountains over 600 meters in height. Not only do the 

 greater altitude and the irregularity of the surface favor the 

 presence in this latter region of northern plants but, as will be 

 seen presently, these physiographic features are accompanied by 

 climatic differences. In the lowland the surface is more nearly 

 level, hills are frequent but high elevations are absent, while 

 except along the two trap ranges, which traverse the region from 

 north to south, precipitous cliffs and deep ravines, such as often 

 abound in the highlands, are scarce. The contrast between 

 highlands and lowland has even been accentuated by the activity 

 of the glaciers; for in the former regions the debris deposited 

 by the retreating ice sheet as a rule is heterogeneous and very 

 unevenly distributed, while in the flatter lowland the till has 

 been buried to a large extent beneath layers of stratified sands, 

 gravels, and clays, so that the structure of the surface soil tends 

 to be much more uniform. Among the most impressive features 

 of the lowland, both from a physiographic and an ecological point 

 of view, are the extensive sand plains — broad, level stretches 

 which in places are utterly devoid of any but the sparsest and most 

 xerophytic plant growth (Fig. 6). Such areas are usually popu- 

 lated by a flora which is preeminently southern in aspect, the 

 northern element being correspondingly scarce. Other instances 

 of a similar correlation between physiographic features and the 

 character of the vegetation might be cited, but the discussion of 

 these is better taken up later in connection with local problems. 

 Except inasuperficial way little is known regarding the influence 



