318 



MEXICO, CENTEAL AMERICA, WEST INDIES. 



In Panama Bay the lowest rise in May and June is about eight feet, whereas it 

 amounts, in November and December, to 23 feet, the yearly average being about 

 13 feet. Owing to these discrepancies the level of the Pacific is sometimes 

 higher, sometimes lower than that of the Atlantic, the greatest possible difference 

 between the two being 10 or 11 feet. Hence in an open canal across the isthmus 

 of Panama, there would be an alternating current, shifting with the respective 

 levels and giving to the canal a constantly varying inflow and outflow. Nor 

 would the movement balance itself, or produce equilibrium, for the average of the 

 oscillations gives to the Pacific a level a few inches higher than that of the 



Fig. 143.— Caledonia Bay. 

 Scale 1 : 400,000. 



o.°\_:f=^ ^% \ * «y^ <>\vi)<.-<\ fîg 



77-50 



West or ureen\A/ich 



77°30- 



Depths. 



6 Miles. 



Atlantic in Colon and Caledonia Bays. Moreover, the rise and fall takes place at 

 different hours in the two oceans, the station in the port of Colon being nine hours 

 behind that of the Pacific. 



Another result of these tidal discrepancies is the different aspects presented by 

 the opposite seaboards. While the Atlantic coastlands are narrow, those of the 

 Pacific develop in some places broad stretches of beach, and are also less rich in 

 coral reefs than the Caribbean Sea, high tides being fatal to most species of 

 polyps. 



Coiba, Cebaco, and the smaller islands on the Pacific side between Burica 

 Point and the Azuero peninsula, all belong geographically to the mainland. 



