364 The American Geologist. December, i898 
the Methow, gave an elevation of 570 feet. Still other aneroid 
readings on the great terrace farther down the Columbia, 
without, however, descending to the river, but referring back 
to the reading obtained at the mouth of the Methow two days 
previous, gave an elevation of 660 feet. This discrepancy of 
about 100 feet, I believe to be due mainly to changes in atmos- 
pheric conditions. 
The great terrace referred to above is, without question, a 
portion of the same terrace visited by me in 1892, below the 
mouth of Chelan river and on the left bank of the Columbia. 
As previously stated, the hight above the river there obtained 
by aneroid, was 700 feet. This measure is probably some- 
what too high, judging by the observations made by me this 
year, and may perhaps be 100 feet in error, but as the hight 
of the terrace above the river probably increases somewhat 
as one follows it down stream, I doubt if the probable error 
is as much as just stated. Mr. Dawson assigns an elevation of 
but 300 feet for the great terrace above the river, and the dif- 
ference between our determinations is from 250 to 400 feet. 
This wide discrepancy is the more surprising as the difference 
between the elevation of the Columbia at the mouth of 
Chelan river, and the surface of lake Chelan, as determined 
by Mr. Dawson, and by myself in 1892, is the same, namely 
325 feet.* 
In volume one, of the reports frequentl)- termed the 
"Pacific Railroad Surveys," there is a paper of Professor 
George Gibbs, in which the Terrace in question is referred 
to as follows, (page 483) : 
''On leaving the Columbia to visit the Chelan lake, our 
route ascended one of these terraces, rising to a height of 
six hundred and forty feet in a single slope, and occupying 
a recess in the hills which bordered it. On reaching the top, 
it proved to be the entrance of a level valle}-, extending 
through the hills and emerging about one hundred and fifty 
feet above the lake." 
As correctly stated by Mr. Dawson, the great terrace of 
the Columbia is a true stream terrace. It is one of a large 
*Recent measurements with engineer levels, made by the Topo- 
graphic Division of the U. S. Geological Survey, show that the surface 
of lake Chelan is 1078 feet, and the mouth of Chelan river 670 feet above 
the sea; the difference is 408 feet. 
