130 bulletin: museum of comparative zoology. 



1-ailway 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 Talcahuano 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 canon. The fine sand deposit continues as a terrace 

 bordering the ri\er, 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 ft.). 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 ri\er Ijefore noted as visible above Gualqui 

 Station. 



Talcamavida Station, 02 kms., alt. 34 M. (1 1 1 .5 ft.) . The fine dark 

 sands form a terrace rising twenty to twenty-fi\e feet above the 

 Station or about 130 to 135 feet above sea-le^■el. The general trend 

 of the gorge from this point to San Rosendo is southeast. Abo\e 

 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.(5 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 km«., alt. 41 M. (134.5 ft.). Top of terrace 

 about twenty feet higher, or about 155 feet above sea-level. 



