ONONDAGA SALT GROUP. 
137 
clayey soil, while the former consist of gravel or an admixture of clay and gravel. These 
hills of gravel are often composed of rounded pebbles, with a large proportion of half-worn 
fragments of the marls and shaly limestones of the Salt group; and where freshly exposed, 
these are constantly crumbling from atmospheric agency. Tn the western part of Genesee, 
and along the whole width of Erie county, the surface is more level, and the hills of gravel 
are less prominent; still, however, it has some features in common with the surface farther 
east. We find slight elevations of loamy or gravelly soil, covered with oaks ; while the broad 
flat clayey bottoms support maple and beech, with some evergreens. 
The prevalence of what are termed “Oak Openings,” or tracts which are covered with oak 
trees rather thinly scattered, but fresh and thrifty; and in other places, tracts of the same 
timber in closer growth, with all the shrubs and smaller vegetation intermingled, indicates a 
fertile soil, and one capable of yielding good crops of grain. Neither is the fact at variance 
with the inference ; for along this whole extent, there is rarely abetter wheat-growing country 
to be found. 
Organic Remains of the Onondaga Salt Group. 
From the nature of this formation, being one of finely levigated mud, with a large proportion 
of saline ingredients, and even free acid, which is destructive to all organisms, and particularly 
to the testacea, it might be inferred that few of these forms would be found. If they have 
ever existed in any considerable numbers, they are no longer visible ; but the stronger pro¬ 
bability is that they have not existed at all, except in the few cases and the rare intervals which 
have been observed. 
Nearly all the forms seen in this group in the Fourth District, are presented in the accom¬ 
panying woodcut; the shells almost entirely removed, casts only remaining. Since the group 
is not identified by its fossils, these are chiefly interesting as presenting the continuation of 
vital energy from the last group upwards. The specimens figured were all collected by Dr. 
Boyd, in Wayne county. 
54. 
[Geol. 4th Dist.] 
