226 AMADEUS W. GRABAU 
ship is, accordingly, that of a progressively overlapping transgres- 
sional series to its basal bed, and this is the interpretation favored 
by all the sections. The Chazy was, in fact, characterized by a 
transgressive or positive diastrophic movement throughout (barring 
possible minor oscillations), and therefore only the higher beds are 
found in the region of late submergence. The thickness of the 
formation beneath the Black River, forms in general a reliable guide 
to the division of the Chazy represented, though of course there may 
be discovered some minor disconformities which would vitiate 
detailed correlations made on this basis in a given region. 
No unquestionable Chazy beds have been reported from the Pacific 
region, where the Trentonian seems to rest directly upon the Eureka 
quartzite in Nevada, and either Siluric or Devonic succeeds the 
Ogden quartzite of the Wasatch, with Mississippic beds succeeding 
the same in the Uintas. The west coast transgression was, therefore, 
less pronounced, the Nevada region remaining still uncovered at 
the end of Chazy time (see map, Fig. 7). If Chazy beds occur in 
the West, they must be sought for in western Nevada and California. 
Tt is, of course, impossible to say how much has been removed by 
late Ordovicic erosion. It is not improbable that the Chazy extended 
east of Eureka, Nev., but was removed again in Upper Ordovicic 
time. 
The Chazy jauna.—At the beginning of Chazy time, the Cham- 
plain gulf was entirely distinct from the Appalachian gulf, there 
being a land connection between the Laurentio-Mississippian con- 
tinent and the united Appalachia and Taconia, or Ancient New 
England continent (see map, Fig-3). The faunas were thus to a large 
extent distinct, representing, in fact, the Atlantic and the southern 
type. The southern type was, in general, the Stones River type of 
fauna; the character of which may be seen by consulting published 
lists. The Atlantic type is-seen in the fauna of the Champlain basin, 
which admits of a threefold division, a lower (Div. A) with Orthis 
costalis; a middle (Div. B) with Maclurea magna; and an upper 
(Div. C) with Camarotoechia plena. 
That these two types of faunas were not wholly distinct in middle 
and later Chazy time is shown by the occurrence of true Champlain 
species of Mid-Chazy age, including Maclurea magna in the middle 
