GEOLOGY. 283 



pebbles of quartzosc nature, and sometimes of pure hyaline quartz. His 

 observations had been made at Newport, R. I., where these distorted pebbles 

 were first noticed, and at V/allingford and Plymouth, Vt., in the Green 

 Mountains. He exhibited diagrams, showing the size, shape, and relation 

 of these pebbles to the conglomerate enclosing them, and the gradual pas- 

 sage of the rounded and water-worn masses into the folia of the schists. 

 At Newport the greatest elongation is in the direction of the strike, but 

 in Vermont in the direction of the dip; in Plymouth he had found the 

 pebbles of one surface continuous with the schistose lamina; of another. In 

 some localises this quartzose conglomerate is intimately associated with 

 gneiss, and seemingly a variety of it; he had no direct proof of this, but 

 believed that there is a continuous series of changes from these quamoso 

 elongated pebbles, through the talcose and micaceous sc-hists, to the gneiss, 

 that are all varieties of the same rock. The gneiss of the Green Mountains 

 has these conglomerates and schists on the east and west sides, the former 

 being the uppermost. He expressed an opinion that these pebbles have 

 been bent since their deposition, and while they were in a plastic state; they 

 are not only elongated, but indented and curved around each other in some 

 localities; the simple curvature of the strata might explain the elongation 

 in the line of strike, but not the other phenomena presented. Some of 

 these pebbles in Vermont are pure quartz. To explain this he invoked 

 the aid of chemistry, and the well-known action of hot water containing 

 alkalies in solution in softening and decomposing silicates, extracting 

 some ingredients and combining others, the form of the rock remaining 

 unchanged. 



Dr. Jackson thought that the smoothness and absence of indentation in 

 these pebbles showed that no change had taken place in the forms since their 

 deposition; they are perfectly polished, as in the stones rolled upon our 

 shingle beaches by the powerful action of the surf. This constant grinding 

 and rolling up and down by the force of the waves would produce various 

 cylindrical forms, and even the crooked and distorted ones exhibited on the 

 diagrams of Mr. Hitchcock; and similar shapes can be seen any day upon 

 the present beaches. Beside, quartz pebbles could hardly have been sof.encd 

 by heat, and, if they were, would have taken different forms from these. 

 The magnetic iron he considered the result of a metalliferous emanation, 

 rising in vapor, as in almost every volcanic eruption, and requiring less than 

 a red-heat. They were parallel to each other and to the line of the strata, 

 because they were thus formed originally. In presence of sea-water, a 

 moderate heat would be sufficient to cause the pebbles to be united by a 

 cement of Woilasronite or silicate of lime. He was averse to an 3* theory of 

 their explanation which requires softening after their deposition. 



At a subsequent meeting of the Society, Professor Rogers, after referring 

 to the character of the conglomerate as presented at Newport, R I , called 

 attention to the steep and alternating dips of the beds of conglomerate in 

 question, and also to the general parallelism of the flat sides of the peb- 

 bles to the planes of deposition, as well as the prevailing uniformity of the 

 direction of their longer axes. He urged that such an arrangement of the 

 pebbles corresponds precisely with the effects of wave and current action 

 on water-worn and partially water-borne fragments during their accumu- 

 lation. The large proportion of pebbles of elongated shape met with in 

 these peculiar beds, wtis, he con.Mdcred, the natural consequence of the 

 mode of disintegration of the original inetmnorphic rocks from which the 



