DESERT REGIONS OF NORTH AMERICA. Al 
During periods of high water the flood passes close against the eastern 
base of the southern end of this range and spreads out as it passes the 
southern end to cover a bare clay plain 6 to 15 miles wide, and by a slow 
current finds its way northward into a bowl-shaped depression, which 
has been designated the Pattie Basin, and the lake thus formed has long 
been known to the Indians as Laguna Maquata. 
As the flood-waters pass down the slope to the laguna a series of 
channels have been eroded in the clay, which are known as Los Barrancas. 
The whole system offers a general parallel to the Salton Basin and Salton 
Lake. Between the two the Cucopa Mountains form a peninsula con- 
nected with high land by a strip running northwest across the inter- 
national boundary. 
The bases of the granite slopes are fringed with palo fierro (Olneya 
tesota), while Terebinthus, Gaertneria, Opuntia bigelovi, O. prolifera, Cac- 
tus, and Echinocactus find suitable habitats to within a few feet of the 
summit, at 3,500 feet altitude. At various places in the granite and con- 
glomerate water collects in cavities and pools, forming tinajas, some of 
which are fairly permanent with the limited demand made upon them. 
No exact study has yet been made of the flora of the Cucopa Range, 
but the preliminary examination seems to show several endemic species 
and that in general the forms present belong to the mainland to the east- 
ward, although a careful analysis may reverse the latter inference. A 
single colony of palms (Neowashingtonia) is reported from a spring high 
up in a branch of a large canyon on the eastern side of the range. 
The Pattie Basin offers some of the most interesting combinations of 
salt lake—of widely varying level—and desert yet examined. The 
extreme limit of the lake is 30 miles in length and 15 in width, but this 
limit is reached only on rare occasions. Marking the upper shore of the 
lake is a belt of mesquite from a few yards to a half mile in width, except 
where the lake comes against the granite slopes. Inside of this are several 
minor beach-lines which show that this lake refills quite frequently, much 
more so than Salton Lake (plate 43). 
The beach of two years since is occupied by a zone of Sesuviumsessule, 
indicating a level at which the lake stood for a few months. With the 
cessation of the inflow, however, the decrease takes place rapidly, with 
deposition of salts, so that occasionally there is presented a bare desert 
with an area of 500 square miles absolutely devoid of vegetation, resem- 
bling in some respects the desert near Great Salt Lake. The movements 
of the fringing zones of vegetation will form a subject for investigation by 
the staff of the Desert Laboratory in conjunction with similar studies in 
the Salton Basin (plate 44). 
The expedition to this region in February, 1907, encountered a ther- 
mal spring, the water of which showed temperatures from 112° to 128° F. 
at the margin of the lake. The surface of the warm pools was matted 
