78 STUDIES IN GEOLOGY, No. 4 



by the Institute Central Meterologico y Geofisico de Chile 

 for Conception (Lat. 36 50' Long. 73 03')- Conception is 

 situated within the coal field, and leaf bearing sandstones out- 

 crop within the city limits, but the only recognizable plant 

 collected at this locality was a species of Sabalites. The 

 determinate plant remains all come from slightly farther 

 south. For the years 1912 to 1915 inclusive the mean annual 

 temperature at Conception averaged 56.25 F., the absolute 

 maximum was in March, 1912, when the thermometer 

 reached 98.25 F., and the absolute minimum was in July 

 of the same year when it sank to 28.4 F. 



There is no snowfall, but much rain. During these years 

 the fewest number of days with rain was 89 in 1912 and the 

 greatest was 135 in 1914. The annual rainfall during this 

 period averaged 54.4 inches, but showed considerable annual 

 variation, from 44 inches in 1912 to 66.9 inches in 1914. 

 The winds are almost exclusively from the north, south and 

 west. 



It is very obvious that the fossil flora recorded from the 

 coal measures could not exist under the existing climatic 

 conditions the fact that the present flora of the region con- 

 tains no elements common to the fossil flora is an ample 

 demonstration of this conclusion. The rainfall is ample 

 and extremes of cold are rare, but the prevailing cloudiness 

 inhibits sufficient sunshine, the summer temperatures are not 

 high enough, and the growing season is too short. 



GEOLOGY OF THE REGION 



Nogues 7 in 1907 divided the sedimentary formations of 

 the Concepcion-Arauco region into three groups the Quila- 

 coya, Arauco and Malleco groups. The first he considered 

 Cretaceous, the second Cretaceous to Eocene and comparable 

 with the so-called Laramie and the Chico-Tejon of western 

 North America, and the third Upper Miocene. 



7 Nogues, A., La formacion lignitifera del sur de Chile, 1895. 



