56 C. F. Hartt—Tertiary Basin of the Marafion. 
bayact, a mile above its confluence with the Marafion. Two 
miles below the mouth of the Ambayacti is Old Pebas. Both 
sites are on the high terra firme.* The right bank of the 
Amazonas opposite the Ambayacu is recent poe low, but far- 
ther down the terra firme appears, and Pichana is situated 
upo 
Phe | bank on which Pebas stands, Mr. Steere says, is about 
100 feet high, that is during the dry season. In front of the 
village the lower strata are hidden from view by a eg of nein 
din 
L The lowest bed seen is a ig clay of which a thickness 
of fifteen feet is uncovered. In the middle is a band three 
feet in eucee Scicaaag shells. 
sae. * fined seam of lignite, six inches in thickness. 
For a few fib bors and below this, the clay is filled with 
vegetable remain: 
Ill. A bed of ue clay, ee feet in thickness, with an 
occasional shell too badly preserved to be remove 
Ly. Blue clay, five feet ak full of fossils. 
bed, ten feet in thickness, of red and white clay, and 
ag without fossils. This forms the surface deposi 
Not far from the ravine where the first section was made, Mr. 
Steere made another as follows: 
I 2or8 ft. of clay full of fossils. 
Il. 106 ft. blue clay. 
III. 3 ft. blue pie filled with fossils. 
IV. : ft. dirty coal. 
V.. 5 or 6 ft. of red and white clay. 
In a ravine in the forest near the vil lage, he made still another 
section, “ finding in descending order” (I quote his own wo: 
‘five or six feet of red and white clay; a vein of dirty coal 
(two feet); blue clay without fossils, ten feet; another narrow 
vein of coal ; eight or ten feet of blue clay without fossils ; ; 
more coal ; beds of clay without fossils; more coal veins.” 
r, Steere visited Pichana, where he found much me same 
structure as at Pebas. At Old Pebas the same beds are seen 
containing beds of lignite, but they appear to be more denuded 
an at New Pebas 
At Iquitos Mr. Steere found similar beds that appeared to be 
the continuation of those of Pebas, but afforded no fossils. 
* Land not laid under water during the annual flood 
+ Lieut. Herndon visited Pebas in 1851. He speaks of the ravines back of the 
town in which a black slate rock crops out, and says that he brought from the 
old town to the new “specimens of black clay slate, that crops out in narrow 
veins on the bank, and made a fire with it, w ei purned all night, with a strong 
bituminous smell.”—Exploration of Valley of the Amazonas, Pt. I, pp. 219-220. 
