No. 14.] FLOWERING PLANTS AND FERNS. 15 



hundred feet above the level of the sea. It is, however, inter- 

 rupted by many sharp ridges running chiefly north and south 

 which rise abruptly much above the general level of the plain. 

 Its upper portion as far south as Middletown is traversed by the 

 Connecticut River. Its rock formation is sandstone belonging to 

 the Triassic age, while the sharp ridges referred to are of trap 

 rock and represent ancient eruptions of lava. The highest of 

 these trap ridges is West Peak of the Hanging Hills, near Meri- 

 den, which reaches an altitude of 1007 ft. above the sea. 



The eastern and western highlands are rugged and hilly, with 

 only comparatively small level areas, and have a crystalline rock 

 formation, being made up for the most part of various kinds of 

 granites, gneisses, schists and limestone. The limestone forma- 

 tion covers a considerable irregular area in the western and north- 

 western parts of the state but is practically absent from other 

 sections. 



It is a well-known fact that our wild plants are not evenly 

 distributed over the surface of the country. Some kinds are seen 

 nearly everywhere, others may be abundant in one region but 

 entirely absent from other sections, while still others are found 

 only rarely, and then but very few together. Inquiry into the 

 causes of this unequal distribution reveals a considerable num- 

 ber of factors entering in. One of the most important of these is 

 the chemical constitution of the soil. Rock formations as the 

 source of soils exercise a marked influence upon plant distribu- 

 tion. Many kinds of plants, it is true, are able to grow and seem 

 to thrive equally well upon a variety of soils, but on the other hand 

 there are many species that flourish only upon certain rock forma- 

 tions and the soils produced from them and are rarely if ever 

 found away from such formations. One of our best examples is 

 seen in the case of those species of plants which grow exclusively 

 upon limestone rocks and in soils rich in lime. In like manner 

 seashore plants which grow only in saline soil form a well- 

 marked group. This relation between plant distribution and the 

 chemical constitution of the soil as applied to our Connecticut 

 plants is understood only in its most general features, and there 

 is here good opportunity for research. The problem is much 

 complicated by the fact that Connecticut soils are practically all 

 formed from transported material. Such material, having been 



