285? Mr D. A. Wells on the 



plane of the former deposit. That such is really the cause of 

 stratification in many cases, I do not dispute ; but that there 

 are other causes which tend to produce, and have produced, 

 stratification equally extensive and varied, is, I think, clearly 

 shewn by the following observations : — 



My attention was first drawn to the subject during the past 

 summer, while engaged in the analysis of soils. By the pro- 

 cess adopted, the soil was washed upon a filter for a consi- 

 derable number of days, in some cases for a period as long 

 as two weeks, and subsequently dried at a temperature of 

 250° F. The residue of the soil left upon the filter, consist- 

 ing chiefly of silica and alumina, was found, after drying, in 

 every instance, to be more or less stratified, and that too by 

 divisional planes, in some cases not at all coincident with any 

 division of the materials, lthough this is apt to take place. 

 The strata so produced were in some instances exceedingly 

 perfect and beautiful, not altogether horizontal, but slightly 

 curved, and in some degree conforming to the shape of the 

 funnel. The production of lamina? was also noticed, espe- 

 cially by the cleavage of the strata produced, into delicate, 

 thin, parallel plates, when moistened with water. These 

 arrangements, it is evident, were not caused by any interrup- 

 tion and renewal of the matter deposited, or by any change 

 in the quality of the particles deposited, but from two other 

 causes entirely distinct, and which I conceive to be these : — 

 First, from a tendency in earthy matter, subjected to the 

 filtering, soaking, and washing of water, for a considerable 

 period, to arrange itself according to its degree of fineness, 

 and thus form strata ; and secondly, from a tendency in earthy 

 matter, consolidated both by water and subsequent exsicca- 

 tion, to divide, independently of the fineness or quality of its 

 component particles, into strata and lamina?. The tendency 

 of this earthy matter is generally to divide along the lines 

 formed by the arrangement of the particles according to their 

 nature or quality : this is not, however, always the case, as 

 was proved by the observations noted, and which is also con- 

 clusively shewn by the examination of almost any stratified 

 rocks. 



In the valley of the Connecticut, where the sandstones re- 



