RIVER TERRACES. 663 
(N, fig. 4.) Along another part of the river, half a mile from this, 
(figure 3,) there were two terraces; the first of eight feet (N, fig. 3), 
two hundred and fifty yards from the river, the second (M, fig. 3) of 
ten feet, two hundred yards. The soil continues to be alluvial for 
fifty yards beyond the last rise; then changes to a granitic sand, and 
slopes into the gentle declivities of the granite hills. A few fragments 
of pumice were found at the top of one of these terraces. 
On the Clammat, I observed no terrace at the place where we 
passed it. 
The Sacramento terraces are far more extensive than those of the 
Willammet. Where we first made the alluvial country, in latitude 
403°, the region, according to our estimate, was between two and 
three hundred feet above the river. From this place the surface was 
pebbly, and sloped very gradually for three miles ; then we descended 
a steep terrace-slope of sixty feet vertical height (M, figure 5). Ina 
Fig. 5. 
M 
N 0 A 
Stee. 
Fig. 6 
M 
a A 
< 
Fig. 7. 
ae zi 
Fig. 8. 
i ee 
SECTIONS ILLUSTRATING THE TERRACES OF THE SACRAMENTO. 
view from here, the upper plain on the opposite side of the river, 
appeared to us to be full three hundred feet high. The terrace of 
sixty feet extends around to the southward. In the lower prairie 
there were two small terraces, one of six feet, (N, fig. 5,) and another 
four hundred yards nearer the river of eight feet (O, fig. 5). The 
