RESIDENCE AT TARAPOTO 53 
cargueros. Our first day's journey, of about 15 
miles, brought us to Lamas ^ — a town of 6000 
inhabitants, near the top of a conical hill, that 
reminded me of similarly situated towns and villages 
in Valencia, as they are depicted in Cavanilles' 
History of that province of Old Spain. 
The Hill of Lamas is plainly volcanic, although 
there is no evidence of eruptions in the shape of 
lava, or any obvious crater, unless certain small 
lakes without inlet or outlet a little below the 
summit may be considered such. The fertile soil 
which covers its flanks, and yields abundant crops 
of every esculent that will bear the climate, espe- 
cially of the indispensable poroto (a kind of 
kidney-bean), consists almost entirely of decom- 
posed shales of divers colours — sulphur-yellow, 
vermilion, purple, slate-blue, and black. These 
shales belong to the Triassic series — near Tarapoto 
I found ammonites of immense size in them — and 
have apparently been broken up by the protrusion 
of a columnar jointed trap-rock, which is here and 
there exposed in the shape of a sloping floor, 
divided with much regularity into squares, rather 
less than a foot on the side, and called by the 
natives ladrillos or bricks. The slope of the 
floors is always towards the apex of the mountain, 
and is inclined to the horizon at from 10° to 30°. 
Overlying the shales there has been a soft white 
sandstone, in thick strata, great part of which has 
been decomposed and carried into the hollows, and 
even into the plain below, by the torrential rains, 
leaving only a few scattered blocks of more tena- 
cious material than the rest. 
1 Lamas : lat. 6° 5' S. ; alt. (convent) 2594 E. ft., (hill-top) 2849 ft- 
