The Great Terrace of the Columbia. — Russell. 363 
the more striking features in the topography of that most in- 
teresting country. 
The Great Terrace of the Columbia. In my report of 
1892* the great gravel terrace, bordering the Columbia in 
the neighborhood of lake Chelan and occurring at many 
localities further up the Columbia, was briefly described and 
the elevation of its surface above the river stated to be 700 
feet. This is an aneroid measurement, or rather the mean of 
several such measurements, and I believed, at the time, was 
as accurate as the method employed could be expected to 
yield, especially when opportunities for rating the barometer 
could be had only at wide intervals. Mr. Dawson states 
positively that the great terrace is but 300 feet above the 
Columbia; whether this is an aneroid measurement or the 
result of some more accurate method is not recorded. 
During the past field season I again examined the great 
terrace referred to, at various localities from the mouth of 
the Methow southward along the Columbia, to where it 
terminates a few miles south of the mouth of Chelan river. 
The terrace is especially well displayed at the mouth of the 
Methow, where it forms a plateau fully a mile-and-a-half 
broad. I again measured its hight, using an aneroid in which 
I had learned to place much confidence. This measurement 
was in duplicate, one set made on descending from the 
surface of the terrace to the river and the other on returning; 
the reading on the return was the same as at the start. These 
observations gave 550 to 560 feet as the hight of the surface 
of the terrace above the river. On the uplands bordering the 
great terrace, at the locality just referred to, there are other 
terraces about 100 feet higher, but these belong in another 
category and have a different history than the great terrace. 
The surface of the great terrace is in several places quite ir- 
regular, on account of the settling of the material composing 
it so as to form basins, but in general slopes gently from the 
bordering uplands to the broken escarpment overlooking the 
river. This difference where the terrace is broad amounts to 
fully 100 feet. Another measurement of the hight of the great 
terrace, at a locality about five miles south of the mouth of 
*Bulletin No. 108, U. S. Geological Survey. 
