Bulletin 3. The flora of the Raritan Formation, 1911 - State of New ...

50 T'HE RARITAN FLORA.
istic fossils of the Magothy and allied Upper Cretaceous formations
over a wide area. This is interpreted as due to the gradual
evolutioi7 of the !Raritan flora, and does not seem of sufficient
weight to warrant the uniting of the Upper Raritan beds with
the Magothy formation, since, as previously mentioned, some of
Newberry's data are questionable, and the only welt-m,qrked stratigraphic
break occurs above the South Aa_boy plant horizon at
the eroded summit of the Amboy stoneware clay.
ORIGINAND RADIaTIOI_.
A great many of the Raritan species appeared at approximately
the same time in the western interior, the Arctic regions
and central Europe. The fact that these floras are all so different
from those of Lower Cretaceous age and that they contain so
predominating an dement of dicotyledonous plants renders any
inquiry into their place of origin or their ancestral forms a subject
of surpassing interest.
There are no adequate data for a phylogenetie discussion which
is not purely speculative, the present desideratum being a knowledge
of those primitive forms from the Older Potomac and an
acquaintance with the flora which flourished while the Sehooley
penepIaiu was being developed-
A num,ber of the immediate ancestors of Raritan species are,
however, represented in the flora of the Patapsco formation of
Maryland and Virginia, others are undoubted immigrants from "
elsewhere. Where did this mid-Cretaceous flora take its origin?
A number of answers are suggested. First, it may have originated
in eastern or central Asial which is an old continental mass,
and spread from there westward into Europe and northeastward
into the Arctic regions and North America. As pi'e_dously mentioned,
it is recorded from Europe, America and the Arctic
regions. It may have originated in Europe and migrated from
thence across the Arctic to Atnerica, or it may have originated
in America and migrated in a reverse direction. "The somewhat
earlier appearance of more modern types toward the close of the
Lower Cretaceous and the somewhat more advanced organization
of the Upper Cretaceovs floras of America as compared with
those of Europe renders the former supposition improbable
NEW JERSEY GEOLOGICAL SURVEY