Block Mountains in Nezv Mexico. — KeyCs. 23 
staying process has enabled partial peneplanation to take place. 
But the mountain blocks have finally become tilted more and 
more. 
Between Tertiary time and the present enormous erosion 
has taken place. The vast plain has been deeply dissected by 
such old mountain-born streams as the Canadian, Pecos, Rio 
Grande, and Colorado. The valleys of these water courses are 
very wide and deep. On the east the Canadian flows 4000 feet 
below the level of the old plain, the Pecos perhaps 2500 feet. 
The Rio Grande about 1500 feet. While the Colorado canyon 
is a mile deep. 
In the Llano Estacado the remnant of the great plain con- 
tains 50,000 square miles. The bolsons are already beginning 
to give way to erosive agencies. In the valley of the Rio 
Grande nearly all traces of the old plain are already destroyed. 
The upland intermontane basins, like the Jornada del Muerto. 
which adjoin the long Rio Grande valley are being deeply dis- 
sected wherever the great river touches their borders. 
New Mexico School of Mines, Socorro, July 30, 1903. 
THE CLIFFWOOD CLAYS AND THE MATAWAN. 
By G. N. Knapp, Trenton, N. J. 
In the Bulletin of the N. Y. Botanical Garden, \'ol. 3, No. 
9, of Sept., 1903, there appears a paper by Edward Berry, on 
"The Flora of the Matawan Formation (Crosswicks clays)," in 
which the author after reviewing what has been written on the 
Matawan and Clay Marl and Raritan proceeds to describe the 
fossil plants found in the clays at Clififwood. N. J., and to dis- 
cuss their significance as a Matawan flora. 
The stratigraphic relations of the Cliffwood clay have long 
been misunderstood, if indeed there has not been a serious error 
in their correlation. 
In the light of the true relation of these Clittwood clays to 
the Raritan and the Clay Marls the significance of this cliflF- 
wood flora assumes a very difl"erent meaning. 
The following quotations from this paper show the author's 
conception of the stratigraphy : 
