THE GREAT FAULT TROUGHS OF THE ANTILLES lOi 



as a land valley, crosses the island to Samana Bay, a distance of 

 240 km. This great valley was named the Vega Real by Columbus 

 in 1494, but now the name is usually limited to the eastern portion. 

 It is very similar topographically to the great valley of southern 

 Haiti. The floor of the valley, less than 25 km. in width, consists of 

 a series of broad plains lying between the Sierra de Monte Christi 

 on the north and the Grande Hilera on the south. The valley is 

 drained by two rivers, the Yaqui del Norte and the Yuma, flowing 

 in opposite directions. 



The geologic structure of the valley has not been studied in 

 detail. Cooke,"^ who has recently visited the region, states that 

 the south front of the Cordillera Sententrional (Sierra de Monte 

 Christi) is a fault scarp which brings up Eocene and Cretaceous 

 rocks high above upper Miocene. The displacement is therefore 

 in the same direction as along the Sierra Maestra fault. Cooke 

 found several faults of slight displacement along the Gurabo River 

 near the southern side of the Vega Real and states that these are 

 probably normal, with uplift on the north. There are other faults 

 of much greater magnitude near the southern side of the Vega 

 Real and in the adjacent part of the Cordillera Central, but no 

 data are now available concerning them. Cooke believes that 

 faulting has been an important factor in shaping some of the 

 boundaries of the Vega Real, but he does not regard the valley as a 

 simple down-dropped fault block. 



The high seismicity of the great northern valley of Haiti was 

 recognized by Scherer, who states that the first great earthquake 

 mentioned in histories of Haiti occurred here in 1564. It resulted 

 in the destruction of Conception de la Vega and Santiago de los 

 Caballeros, two cities in the Vega Real about 30 km. apart. In 

 1783 the principal church at Santiago was partly thrown down by 

 an earthquake and several buildings were destroyed. 



The earthquake of May 7, 1842, was one of the most severe 

 recorded on the island. Destruction was greatest at Cap Haitien, 

 a city of ten thousand inhabitants, which lost half of its population. 

 The intensity was almost equally as high at Mole St. Nicolas, 



^ Dr. C. W. Cooke kindly furnished information concerning the geologic structure 

 of the Vega Real in letters dated January 26, and October 5, 1920. 



