130 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
railway stations and distances from the terminus at Talcahuano are 
from the official map of the railways of Chile. The estimates of the 
elevations of the terraces are approximate only except at San 
Rosendo where measurements were made with an aneroid barometer. 
Talcahuano, O. kms. Altitude 3 M. (9.8 ft.). This is the elevation 
of the border of the delta of the Rio Bio Bio. 
Los Pexales, 7 kms. alt. 6 M. (19.6 ft.). This is a point on the 
plain midway between Taleahuano and Concepcion. 
Concepcion, 15 kms., alt. 9 M. (29.5 ft.). This is the elevation of 
the railway station near the river. The plain rises north of this point 
to an elevation of about forty-five feet. 
Chiguayante, 25 kms., alt. 18 M. (59 ft.). This Station is within 
the gorge where the river flows northwest. Above this point a stony 
terrace appears. 
Gualqui Station, 38 kms., alt. 21 M. (68.8 ft.). Terraces of allu- 
vium judged to rise from thirty to thirty-five feet above railway, or 
100 feet above sea-level. At about 120 feet above sea-level there is a 
sloping dissected terrace in the decomposed bed rock of the gullied 
sides of the cafon. The fine sand deposit continues as a terrace 
bordering the river, apparently a continuation of the deposit forming 
the Concepcion Plain. Above this terrace the side walls are deeply 
gullied. 
Quilacoya Station, 48 kms., alt. 25 M. (82 it.). The terrace here 
rises to about 105 feet above sea-level, at its edge. The railroad runs 
on a deposit of the dark sands. Old rock remnants of a sloping terrace 
are to be seen on the ravined walls of the gorge, apparently indicating 
an old baselevel of the river before noted as visible above Gualqui 
Station. : 
Talcamavida Station, 62 kms., alt. 34 M. (111.5 ft.). The fine dark 
sands form a terrace rising twenty to twenty-five feet above the 
Station or about 130 to 135 feet above sea-level. The general trend 
of the gorge from this point to San Rosendo is southeast. Above 
this Station in the terrace large angular stones, cobbles, and gravel 
appear, indicative of flood conditions with ice-rafts,— typical glacial 
river deposits. 
Gomero Station, 69 kms., alt. 38 M. (124.6 ft.). The edge of the 
terrace is here about twenty feet above the railway, or about 145 feet 
above sea-level. Heavy gravel beds are exposed along the river above 
this point, with waterworn cobbles. 
Bunaraqui Station, 76 kms., alt. 41 M. (134.5 ft.). Top of terrace . 
about twenty feet higher, or about 155 feet above sea-level. 
