388 APPENDIX. 



action of oceanic masses of water, operating at an ancient 

 period. 



The latter opinion appears to be generally adopted. Dr. 

 Mitchell, in reference to northwestern boulders, attributes their 

 distribution over secondary regions to the draining of interior seas 

 or lakes. Mr. Hayden, in his Geological Essays^ refers them to 

 the action of oceanic currents setting "from north and east to 

 south and west," 



Subordinate and Equivalent Strata. — These constitute 

 the most intricate subjects of reference. They are either adjuncts 

 or residuary deposits of leading formations. But their order, as 

 accompanying series, must sometimes be sought for by a previous 

 determination of the formations themselves. Could we certainly 

 know, for instance, that the sandstone of "Western New York is 

 or is not the true coal-sandstone, or the limestone is or is not the 

 carboniferous limestone, it would at once direct to positive eras, 

 and serve to impart confidence in the prediction of unknown 

 deposits of an important character. But, in order to fix the 

 formations, it is often the safest mode of procedure to employ the 

 subordinate and local deposits as evidences of the character of the 

 formations embracing them. 



Gypsum. — A stratum of gypsum of the plaster of Paris kind — 

 that is, consisting of an admixture of the carbonate with the sul- 

 phate of lime — occurs on the banks of the Canandaigua outlet. 

 It has been chiefly explored in the township of Phelps, Ontario. 

 In visiting the principal bed (1820), I found the following order 

 of deposits composing the banks of the outlet : — 



1. Alluvial soil of a dark, arenaceous, and mellow character, 

 having small stones of the primitive kind sparingly interspersed, 



, two and a half to three feet. Cultivated in improved farms. 



2. Shelly limestone, of an earthy, dull-gray color and loose tex- 

 ture, in layers, three feet. 



3. Limestone of a more firm character, but still shelly, or rather 

 slaty, fissile, and easily quarried, six feet. This stratum contains 

 iron pyrites in a decomposed state. Also, nodular or kidney- 

 shaped masses of what the quarrymen call plaster-eggs — apparently 

 snowy gypsum. 



4. Plaster of Paris, ten feet. This stratum yields granular, 

 earthy, fibrous, and foliated gypsum. It is the first two varieties 



