156 References to North American Localities. 



Alluvion is divided into Cailhuteux, gravel, (as below the sloop- 

 dam in Troy.) Limoneux, loam and fine sand, (as at and near 

 the Overslaugh below Albany.) Phytogene, peat and vegetable 

 loam, as in all cases where vegetable matter has become pulveru- 

 lent or turfy. A remarkable locality is to be seen along the bank 

 of Erie Canal, west of Nine-Mile-Creek, for several miles. It 

 generally overlies the tufa in that locality ; but it is not necessa- 

 rily a relative position. 



The limit between the tertiary and diluvial, and between the 

 diluvial and alluvial, is truly a matter of common sense. I would 

 apologize for attempting this common sense limit, were it not ex- 

 cusable on the ground of uniformity. 



With the exception of Brongniart's division of his secondary 

 strata into upper and lower, I think 1 have referred to satisfactory 

 American localities, for finding out the true limits of all his class- 

 es. It is true that every geologist cannot afford time for visiting 

 the localities referred to : but geology as a science, is a book of 

 vast geographical extent, and no index to this department of the 

 study of nature, can be sufficient to present to the student, a view 

 of the great book of this giant science. State geologists are dif- 

 ferently situated. 



With the hope that this abstract from my journals of about 

 seventeen thousand miles of travel, (more than a moiety at the ex- 

 pense of the Hon. S. Van Rensselaer,) arranged according to Brong- 

 niart, may be useful to the zealous student, and juvenile state 

 geologist, I subscribe myself the humble servant of all zealots in 

 the science. Amos Eaton. 



Rensselaer Institute, Troy, N. Y., June, 1840. 



P. S. — Catskill Mountain presents a fair exhibition of the Al- 

 legany, Catskill, and Helderburgh range, at a point nearly west 

 of the village of Catskill ; taking a transverse section of about 

 fourteen miles. The rock on the bank of the river east of the 

 village is transition grauwacke. This passes under the calcifer- 

 ous sandrock, best for examination and its usual abundance of 

 quartz crystals, two miles north of the village. Both rocks pass 

 under corniferous limerock at two miles west of the village, on 

 the Mountain road. The last passes under the true Psammite of 

 Brongniart, which contains bituminous shale and a little coal 

 resting on corniferous limerock. This is seen in the south bank 

 of Lake Erie, at the water's edge and a little below ; on Seneca 

 Lake, Cayuga Lake, (fcc. 



