Fauna of the Lower Cambrian. — James. 85 
Upper Cambrian strata are unconformably superjacent to the Al- 
gonkian and Archean rocks, over areas where the Middle and 
Lower Cambrian formations are absent ; (4. ) the strata of the 
Middle and Lower Cambrian are conformabh* beneath the Upper 
Cambrian on the eastern and western sides of the present continent 
in all sections where the three divisions are present." (p. 557.) 
This portion of the paper is illustrated by one map showing the 
general distribution of Lower Cambrian strata, and b\' a second 
upon which are shown a number of sections from tj-pical areas. 
These indicate the relations between the base of the Lower Cam- 
brian and the rocks beneath, as well as the relation between the 
top and the overlying series. While a theoretic section across the 
continent from east to west shows the troughs in which the Lower 
Cambrian rocks were deposited, and indicates the presence of a 
land area between the Adii'ondacks and the Kocky mountains. 
Other illustrations show the uncouformit}^ between the Potodam 
and the underlying Archean of the Mississippi valley. The gen- 
eral conclusion arrived at is that the interior of the continent, prior 
to Upper Cambrian time, stood at a relatively high level. This 
seems to be proven by the accumulation of more than 10,000 feet 
of sediment in Nevada and in the Wasatch mountains, by the 
great thickness of strata of Lower and Middle Cambrian age on 
both the east and west sides of the continent, and the absence of 
these rocks in the interior. Mr. Walcott further sa3-s : ' ' That 
the Upper Cambrian sea was transcontinental is shown by the 
presence of the same species of Upper Cambrian fossils in similar 
stratigraphic relations to strata containing the Ordovician ( Lower 
Silurian) fauna in the valleys of the St. Lawrence and lake 
Champlain, and on the slopes of the Adirondacks in New York ; 
in the southern Appalachian region of Tennessee and Alabama ; in 
the upper Mississippi valley in Wisconsui and Minnesota ; in the 
sandstones and limestones of Texas and the Black Hills of Dakota, 
and in the limestones of Nevada and Montana." (pp. 561, 5G2. ) 
It is not argued that the fauda of these widely separated 
localities were contemporaneous, but that the}' have identical 
stratigraphical relations ever3-where to the fauna above, and to 
that below when it is presnt. 
In the notice of European deposits a map is given, copied from 
one by Ilicks, upon which is shown the distribution of the for- 
mation and several typical, vertical sections. • 
A resume of the fauna shows the existence of G7 genera, 1(»5 
