144 THEORY OP THE EARTH. 



The river Adour, which is formerly known to have 

 passed Old Boucat to join the sea at Cape Breton, 

 is now turned to the distance of more than two 

 thousand four hundred yards. 



The late M. Bremontier, inspector of bridges and 

 highways, who made several extensive works to 

 endeavour to stop the progress of these downs, 

 estimated their progress at sixty feet yearly, and 

 in some places at seventy-two feet. According 

 to this calculation, it would require two thousand 

 years to enable them to arrive at Bourdeaux ; and, 

 on the same data, they have taken somewhat more 

 than four thousand years to reach their present 

 situations.* 



The turbaries, or peat-mosses, which have been 

 formed so generally in the northern parts of 

 Europe, by the accumulation of the remains of 

 sphagnum and other aquatic mosses, afford another 

 means of estimating the time which has elapsed 

 since the last retreat of the sea from our present 

 continents. These mosses increase in height in 

 proportions which are determinate in regard to 

 each. They surround and cover up the small 

 knolls upon which they are formed; and several 

 of these knolls have been covered over within the 

 memory of man. In other places -the mosses gra- 

 dually descend along the valleys, extending down- 

 wards like the glaciers ; but these latter melt every 



* Memoir of M. Brsmontier. 



