254 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



disturbances and intercalations, and the ample elucidation it has 

 received from geological observers of the highest class, have rendered 

 it a most convenient and trustworthy standard of comparison with 

 similar basins. In the early palaeozoic times, we may here remark, 

 and especially at the period of the Lingula-fiags (or Potsdam Sand- 

 stone, their New York representative), a waste of shallow waters 

 almost wholly overspread the earth. Here and there were lands, 

 probably low, composed of the older metamorphic rocks, and forming 

 the widely separated and devious coast-Hnes of immense sea-basins, 

 wherein were deposited mineral sediments, chiefly through the me- 

 dium of vital processes, but greatly also by currents, — the coarse 

 near to, and the fine remote from, the dry land, — such action com- 

 mencing from the moment any given region was immersed beneath 

 the waters. These deposits constitute the sedimentary strata, the 

 subject of the observations now about to be made. Those of New 

 York may be usefully arranged under the following seventeen heads, 

 namely : — ^ 



Siliceous Conglomerate. 

 Siliceous Grit. 

 Siliceous Sandstone. 

 Argillaceous Sandstone. 

 Micaceo-argillaceous Sandstone. 

 Ferruginous Sandstone. 

 Iron-ore. 

 Calcareous Conglomerate. 



Pure Limestone 



Calcareous G-rit. 

 Calcareous Sandstone. 

 Argillo-calcareous Shale. 

 Calcareo-argillaceous Shale. 

 Micaceo-argillaceous Shale. 

 SiHceous Limestone. 

 Magnesio -argillaceous Limestone. 

 Argillaceous Limestone. 



These seventeen materials, varying in the proportions of their ingre- 

 dients, constitute the whole sedimentary basin of New York. They 

 are good types, — some one or more occupying each of the group- 

 sections into which this basin has been divided. Magnesia enters 

 largely into the composition of some of the sandstones and lime- 

 stones of the western continuations of this basin (Wisconsin, &c.) ; 

 but not, as far as I am aware, within the limits of New York, 

 excepting in the Onondaga- Salt Rocks. The Clinton iron-ore of 

 New York is of workable value ; it is an oolitic lenticular clay- 

 iron-ore (Vanuxem, p. 83). 



The manner in which this distribution has taken place is seen at 

 a glance in the Table of mineral characters of the palaeozoic strata of 

 this State (No. I.). This Table exhibits, first, in separate columns, 

 the variations in composition undergone by each section, giving the 

 predominant character of each in the last column. 



The following inferences may be drawn from this Table : they 

 seem to be of some importance. 1. The three great mineral forms, 

 siliceous sand, clay, and lime, are nearly equal in quantity. The 

 other minerals are rare and iminfluential, except iron and magnesia, 

 which, however, are in less quantity than those first mentioned. 2. 

 The great classes of rock, arenaceous, calcareous, and siliceous, are 

 usually massed together ; but not often in a state of purity. 3. 

 The hthological grounds on which the State -geologists of New York 

 have based their stratigraphical arrangements are well defined. 4. 



