274 
GEOLOGY OF THE FIRST DISTRICT. 
resemblance to the green marls of Virginia, Maryland, Delaware and New-Jersey. Most 
travellers through that region, and from the gold region to Baltimore, who have noticed the 
mineral characters of the tertiary and newer secondary formations, can scarcely have failed 
to see the striking similarity of many of them to the recent wrecks of those disintegrating 
rocks. 
Physical causes of transport. It has been shown in the chapter on the drift deposits, that a 
current has, in all former time since the ocean has been in its bed, and the general form of the 
American coast similar in its general features to the present, flowed from the Gulf of Mexico 
to the northward along the eastern coast; and also that a current has flowed from the north 
towards the south. These currents, now under consideration, as tending to influence the 
transportation of materials beneath the level of the ocean, are local examples of parts of the 
equatorial and polar currents. These currents, in consequence of dynamical laws that have 
been explained under Drift deposits, are as permanent as the rotation of the earth on its axis, 
and the existence of the ocean. The eastern part of the United States, on which the upper 
secondary strata are deposited, bear incontestible evidences of having been covered by the 
waters of the ocean at the time of the deposition of those strata. 
The materials of the depositions now under consideration, bear evidences of transportation 
from a southwestwardly direction (except Long island, the reasons for which will be attempted 
to be shown in another place). The current of the Gulf stream, which is the name of a 
branch of the equatorial current at the present time, is believed sufficient to transport most of 
the materials of the strata under discussion, except where there are evidences of local causes 
for coarser deposits.* 
Why marls and fossils are not common on Long island. The question may here be asked, 
if the deposits below the drift of Long island are equivalent to those of New-Jersey, &c., 
why do we not find the marls and fossils there ? 
It has been shown in the article on the drift, that a branch of the Polar current has flowed 
at the drift epoch, and probably from a very early period of geological chronology, (as facts 
yet to be adduced will show,) through the Champlain and Hudson valley. This current 
meeting the Gulf stream in New-Jersey, would tend to check its velocity, and cause deposi¬ 
tions of the matter it was transporting ; and the northern current being colder would neces- 
» TABLE SHOWING THE TRANSPORTING POWER OF CURRENTS. 
Power of TRA^ 
Jes sanVL”coarse as flaxseed,' 
res pebbles an inch in diameter, • •••■ 
res angular fragments two and three 
