412 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 
or Amotape hills (see pl. 2). The lithologic characters of the 
beds vary considerably, consisting of shales, sandstones, conglomer- 
ates, and in some places beds filled with shells and occasionally 
there are coral reefs. The changes observed in the nature of the 
formation are due to the varying distance from the shore at which 
they were deposited and to the deepening and shallowing of the 
water during the time of sedimentation. It is probable that the 
materials were derived from the mountainous area which during 
Tertiary time formed the ocean shore to the east, approximately 
where now are the foothills of the Andes. 
The strata of the formation are not much lithified and the shales 
and sandstones grade into each other and into conglomerates. In 
the Brea hills the Amotape formation has been uphfted in an 
anticline, giving good exposures where the stream valleys have been 
eroded. The thickness of the beds has not been studied carefully, 
but from the outcrops seen it is safe to say that on the average it is 
not less than 1,000 meters, although the thickness may be much less 
in some places and greater in others, depending upon the distance 
from the Tertiary shore. : 
Fossils are very abundant and well preserved at many places, one 
of the most noticeable being a large oyster which is found in such 
great numbers that it is used locally for burning lime. 
The principal mineral substance which is exploited at the present 
time is petroleum, of which there are superfiicial indications at two 
places called la Brea and la Breita. The productive localities are 
Negritos, Lobitos, and Zorritos located on the coast. Besides these 
some prospecting has been done farther inland. It has been reported 
that coal has been found at various localities within the hmits of 
this formation. ‘That which the writer examined at Bahia de la Cruz 
is a lignite, and prospecting failed to reveal a bed of any importance. 
The writer has been assured that north of Sullana, at the base of 
the Brea hills, a good quality of lignite has been found and of suf- 
ficient thickness to warrant its extraction. However, the bed has 
never been worked and further exploration would be necessary to 
prove its commercial value. The Amotape formation contains va- 
rious mineral salts, especially gypsum, which render the water 
obtained from it unfit for domestic uses. The formation extends 
throughout the plains region from the Ecuadorian border southward 
into the table-land to the east of Pita. Undoubtedly it extends far- 
ther south, but the exposures are obscured by drifting sands and 
have not been studied by the writer. It may be noted in this con- 
nection that Wolf in his geologic map of Ecuador has erroneously 
indicated a recent formation in the plains region to the north of the 
Brea hills. 
