27 
CLINTON GROUP. 
ot the others in very shallow water. In many instances, the marks of what appear to be wave¬ 
lines are still preserved upon the surface of the layers. These markings have been regarded as 
evidences of a line of beach at the period of the Medina sandstone, and the strata under con¬ 
sideration follow in immediate succession to that period : they arej moreover, associated with 
pebbly beds which were probably littoral. 
Some of these continuous tracks or trails I have been disposed to refer to the gasteropodous 
mollusca ; but on comparison with such trails made upon recent beaches, they do not all appear 
to have had such an origin, and there are likewise other animals which produce somewhat similar 
tracks. Many of these markings resemble, in their tortuous direction, and in the manner of 
crossing and recrossing the same line, the trails produced by the little Idotea upon the beaches 
of our present coasts. Some of them, however, must have been made by animals of different 
character. It is perhaps impossible to ascertain satisfactorily, at the present time, the origin of 
all these singular and interesting markings; but by calling attention to their existence in these 
ancient strata, we may perhaps be able to find analogous markings upon our recent beaches. 
It should be noticed that all these markings are preserved in the arenaceous beds ; and though 
they may have originally existed in the softer shaly beds, they would not now be visible. That 
they have been sometimes made in the shaly layers, we have good evidence in the casts that are 
often preserved on the lower side of the harder layers. The tracks or trails in question are always 
seen upon the upper surface of the layers, and are not to be confounded with those curious and 
variable markings so often found in relief upon the under sides of the harder layers, where they 
rest upon shale. 
These markings occur in greater or less number and perfection throughout the entire extent 
of the group, so far as I have been able to make examinations, but they are more perfect and 
abundant in Herkimer and Oneida counties. The three characteristic varieties figured in the 
plates have been found in a single locality. The condition of the strata is very variable, and 
frequent alternations of shaly and arenaceous deposits are the characteristic features of this part 
of the group. The mass here consists in its lower part of a coarse conglomerate with green shaly 
matter intermixed, together with a bed of iron ore : still higher is a thick mass of shale, and 
above this commence alternations of shale and thinbedded sandstones. It is in the latter that the 
trails are most abundant and best preserved. 
PLATE XI. Figs, lab, 2 a b, 3 & 4. 
Fig. 1 a, is a continuous trail, made by a single individual moving along a slightly elevated 
ridge upon the surface of the sandstone. The trail continues along this ridge, often descending 
slightly from the higher part, but always returning again, and recrossing itself many times in 
succession. Beyond that portion of the stone figured, the trail leaves the ridge, crosses a slight 
depression, which must have been more moist, or where water was still standing (as the trail is 
very faintly perceptible), and again ascends to another elevated portion of the slab, where it 
continues meandering about over a considerable space. 
