320 H. S. Williams—Channel-fillings in Upper Devonian Shales. 
channel across the bottom and up the other; some of the lines 
are fine and thread-like and appear entirely uninfluenced by 
the depth of the channel down and across which they swept. 
These lines puzzle me much for explanation, and the only 
suggestion which appears to me worth offering is that of a 
swiftly moving tide or current trailing seaweeds or particles 
rapidly with it over the bottom. 
To explain the channel-fillings there occurs to me only one 
series of events which begins to cover the facts. The uniform- 
ity; structure, directness and great number of the channels 
seems to preclude the idea of a rapidly flowing stream across a 
beach, and the continuity of the imbedding strata seems consist- 
ent only with under-water work. 
he suggestion I have to offer is, that these channels were 
caused by the scratching of icebergs on the shoals represented 
by the imbedding shales; that the channels were then scooped 
cleanly out of the mud of the bottom; that the flow or runnel 
marks were caused by the same ocean current which bore along 
the icebergs, and perhaps increased in the wake of the berg. 
e deposit of sand in the channels was due to the catching 
of the heavier sand (in the cavity thus formed) more rapidly 
than on the general surface represented by the thin arenaceous 
layers above; and I suppose it therefore to have been filled 
ts. 
Before closing, it may be interesting to mention that the 
richest locality known of the commoner of the beautiful and 
large fish pee closely resembling the plate © of the ventral 
ewberry’s Dinichthys Terrell from the Huron shale 
of Ohio (see Pal. Ohio, vol. ii, chart No. vi, and p. 8 : 
specimen found at Ithaca is about half the size of the Ohio 
specimen figured. The shales in which the channel-fillings are 
seen is characterized by the presence of a Lingula whic 
believe to be new, at least as a variety and probably aa 8 
species, and which I propose to describe at another time. 
were ys 
kee Sra Oe ee 
tenth a as 
Ee tre mb 
== re, 
ee 
Speco os has 2 
igs a a Ra apt oa SEN a a ta a hen 
Pee AR Re Re eC ee 
