20, 8 Schenck: Physiography and Geology of Samar 259 
the seas. At places, Miocene limestone must have stood out as 
prominent headlands. The wave action that wore away the 
rock partially rounded the fragments that contained this char- 
acteristic Miocene fossil, and then cemented a new rock, including 
in the product rounded pebbles of igneous formations; or it may 
‘be that at places the ‘burden of the streams failed of influence, 
and there was formed, instead, a new limestone out of the frag- 
ments. Stream action may have accomplished the same results. 
The Pliocene was followed by an interval of erosion. In the 
Pleistocene seas corals again lived, and in these waters marls, 
shales, and sandstones were consolidated. During this period 
the marine terracing took place and subsidence of portions of 
the island occurred. 
The Pleistocene is separated from the Recent by a marked to- 
pographic unconformity, and in this, the latest time, the domin- 
ant features again appear to be uplift, subsidence, and the 
growth of reef corals; and to-day Samar is subjected to great 
erosion accompanied by the conveyance of vast quantities of 
material by the numerous streams into bays such as the one at 
Wright, which is being filled gradually. Thus, youthful are 
transformed into mature shore lines. If we project the condi- 
tions of to-day into the past, we find warrant for the belief that 
in late Tertiary and Recent times Samar has been unstable and 
that life in the shallow waters bordering the coast has always 
been abundant. 
ECONOMIC GEOLOGY 
It has been pointed out that the ragged island of Samar is of 
relatively recent origin and that sedimentary rocks are by far 
the most abundant ones. The economic mineral products of 
Samar remain to be discussed under metallic and nonmetallic 
minerals. A summary of this entire subject is simple and may 
be expressed by the statement: “No commercial deposits were 
encountered.” ‘ 
Metallic minerals—Our party found no important economic 
metallic minerals in Samar, and this is what would be expected, 
judging from the character of the formations observed. Gold 
has been reported from the mouth of Pambujan River and from 
other streams, but the only gold seen by me was a microscopic 
fleck in a reworked limestone conglomerate. Copper is reported 
on Capul Island. It is said that lead occurs at places. I saw . 
no formations that hold any promise of metallic productivity. 
It must be borne in mind, however, that the reconnaissance did 
