Observations on Terraces. 87 



less needed here, especially if we consider the wide theory based 

 upon the facts. And I see not, by what authority, a private 

 "protest" can be entered against such a course of investigation. 

 Marine relics are too common a proof of elevations of coasts in 

 all climates to be pronounced necessarily absent upon an uncertain 

 general principle. 



An examination of American terraces, has led me to believe 

 that in general, the terraced plain corresponds in its seaward slope 

 with the descent of the river, although apparently horizontal. 

 The most skillful use of the best instruments is often necessary 

 to test the horizontality : for the descent of most of our rivers, 

 for a considerable part of their course is less than one foot in a 

 mile. The Connecticut, from Springfield to the sea, falls sixty- 

 four feet, which is one foot a mile (not reckoning the irregulari- 

 ties of its line) ; deducting for Enfield Falls, thirty feet, it leaves 

 only £ a foot a mile. The same river at Hanover, 175 miles in 

 a direct line from its mouth, is 365 feet above the sea ; and de- 

 ducting 30 feet for Enfield Falls, 50 feet for Hadley Falls, 70 

 for Miller's and Montague's, 50 for Bellows, and 36 for White 

 River, and also deducting 30 miles in length for the space oc- 

 cupied by these several falls, it leaves for the rest of the descent 

 about fj of a foot a mile. The Mississippi from the mouth of 

 the Ohio to the Gulf of Mexico, a distance of 1100 miles, has an 

 average descent of only 3£ inches to the mile, and the Ohio in 

 950 miles, averages but 5 inches. 



Again, if horizontality is proved, as apparently in Glen Roy, 

 the question of a lake origin comes up for investigation. 



Hence the apparent horizontality insisted upon, may still re- 

 quire further examination ; and if absolutely demonstrated for 

 all the various terraces described, the question of origin yet re- 

 mains open for investigation. 



The proof as regards Scotland is not so satisfactory but that 

 some prominent geologists who have been on the ground — Mac- 

 culloch, Buckland, Agassiz, Mr. David Milne, and others— have 

 taken a view directly opposed to that of Mr. Chambers. 



The continuity of line between a seashore and inland terrace, 

 cannot prove the seashore origin of the whole. I have already 

 shown that the same elevation must produce simultaneously 

 marine and river terraces. If the country forming the valley 

 °f the Mississippi were raised, from the Gulf of Mexico north, 

 there would in some places be a terrace along the sea ;— there 

 would also be rapid excavations by the descending river en- 

 croaching on its planes either side, and causing ultimately new 

 bottom-lands many miles in width, with a terrace slope as their 

 boundary ; and the terrace slope of the river would be neces- 

 sarily continuous with the " benches" of land bordering the 

 sea and estuary. Will this continuity prove the whole to have 



