Smithsonian miscellaneous collections . by the average thickness of the rings of about 40trees from five separate localities. Figure 30 shows these only is a 23-year cycle apparent, but many details are reproducedwith such moderate alterations of phase and amplitude as to givereasonable certainty of the veridity of these minor features in all fourcycles. As remarked above, the amplitudes of these features whichcompose the cycles tend to diminish as the trees grow older. 23. A Test of the 23-YEAR Cycle in Pleistocene Varves In a paper by C. A. Reeds, he gives many pages of illustrat
Smithsonian miscellaneous collections . by the average thickness of the rings of about 40trees from five separate localities. Figure 30 shows these only is a 23-year cycle apparent, but many details are reproducedwith such moderate alterations of phase and amplitude as to givereasonable certainty of the veridity of these minor features in all fourcycles. As remarked above, the amplitudes of these features whichcompose the cycles tend to diminish as the trees grow older. 23. A Test of the 23-YEAR Cycle in Pleistocene Varves In a paper by C. A. Reeds, he gives many pages of illustrationsrepresenting the march of the thickness of glacial varves near theConnecticut and Hackensack Rivers. Independent measurements byAntevs and Reeds are shown. Continuous series represent the presentthicknesses of these varves resulting, it is believed, from annualweather-reactions extending in unbroken sequence for nearly 1,000vears. Ann. Rep. Smithsonian Inst. 1930, pp. 295-326, 1931. 72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94. Fig. 30.—Cycles of 23 years in tree-ring widths. Individual cycles ofyears show features which are found preserved in the mean of four cycles, or 92 years. NO. 10 SOLAR RADIATION AND WEATHER STUDIES ABBOT 73 The varves are supposed to have been formed as follows: DuringPleistocene glaciation considerable melting of the surface of the ice,as well as copious rainfall, took place during the summer of each produced glacial torrents which scoured the sides of the glacialvalleys and carried down sediment. Settling occurred in the quietlakes which at the foot of the glacier intercepted the torrential such settling the coarser particles reached bottom first, and thefiner particles were superposed thereon. The settling took place mainlyin the colder months after the melting had greatly diminished andsnow rather than rain fell, so that the turbulent streams nearly this way each year a layer of sediment was deposited, coarser a
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