156 References to North American Localities. 
Alluvion is divided into Caillouteur, gravel, (as below the sloop- 
dam in Troy.) Limoneur, 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 wpper 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 peolopiat 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- 
sd situated. 
the hope ‘that this abstract from my journals of about 
ium thousand miles of travel, (more than a moiety at the ex- 
pense of the Hon. S. Van Repsasiaet,) 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 AF 
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 erystals; 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 © 
Brongniart, which contains bituminous shale and a little coal 
ig on corniferous limerock. This is seen in the south bank 
Erie, at the a mes and a little below; on Seneca 
the 
