Forest physiography; physiography of the United States and principles of soils in relation to forestry . Cretaceous peneplanation and the general occurrence ofsoft sandstones and shales have led to the development of a lowland(Tertiary) between an eastern and a western upland of crystalline rockof sufficient resistance to preserve traces of the peneplain. The greaterpart of the lowland is drained by the Connecticut River, although largeportions are drained also by the Quinnipiac and the Farmington. GEOLOGIC STRUCTURE The lowermost rocks which constitute the Triassic formation of theConnecticut
Forest physiography; physiography of the United States and principles of soils in relation to forestry . Cretaceous peneplanation and the general occurrence ofsoft sandstones and shales have led to the development of a lowland(Tertiary) between an eastern and a western upland of crystalline rockof sufficient resistance to preserve traces of the peneplain. The greaterpart of the lowland is drained by the Connecticut River, although largeportions are drained also by the Quinnipiac and the Farmington. GEOLOGIC STRUCTURE The lowermost rocks which constitute the Triassic formation of theConnecticut Valley consist of a series of 5000 to 6500 feet of coarsesandstone and conglomerate and a limited amount of shale. Thematerial consists of the waste of granite and other crystalline rockssimilar to those upon which the deposits lie. Intruded in these andgenerally not more than 200 to 300 feet above the base of the formationare the trap sheets of West Rock Ridge in the south and of the Barn-door Hills in the north. The sheets are from 500 to 600 feet thick in 654 FOREST PHYSIOGRAPHY XKw H.\Misiin;r. Fig. 263. —Relation of the Connecticut Valley lowland to the bordering uplands, the extent of the low-land, principal relief features, and drainage systems. (Russell, Davis, and others, U. S. Geol. Surv.) OLDER APPALACHIANS (NORTHERN DIVISION) 655 places, but generally somewhat less. Succeeding the lower memberswith their intruded trap sheet is a series of sandstones, shales, impurelimestones, intercalated with a series of three trap sheets. The lowertrap sheet is called the anterior sheet and is generally about 250 feetthick, but thins out and disappears before reaching the northern bound-ary of Connecticut. Above the anterior sheet are shales and sandstones
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
