Gulf of California — Roden 
23 
sary to assume the existence of a ridge run- 
ning SSE between Angel de la Guarda and 
Tiburon to account for the differences (Sver- 
drup, 1941). There are two large islands in the 
Gulf— Angel de la Guarda and Tiburon — 
both with elevations exceeding 1500 m. 
The coast along Baja California is very 
steep and flanked by numerous islands and 
rocks. Off Rio Colorado and northern Sonora 
the coast is less rugged and possesses a wide 
shelf. Along Sinaloa the shelf narrows again 
and disappears at Cabo Corrientes. 
The Gulf remained scientifically unknown 
until fairly recent times. Prior to the coming 
of the conquistadores, the Gulf area was in- 
habited by different Indian tribes who lived 
by fishing and undoubtedly had some local 
knowledge of the currents and the general 
appearance of the water. Their observations 
are, however, lost because they had no written 
records. 
With the coming of the Spaniards, trade 
developed between Gulf ports and the Far 
East (Hakluyt, 1598) and various captains 
entered the Gulf with lead and line. The first 
written records are therefore found in the 
ships’ logs of the early seafarers. Scientific 
exploration began in 1889 when the U. S. 
Fish Commission steamer "Albatross” (Fig. 
2) entered the Gulf to make a few hydro- 
graphic stations, especially in the northern 
part (Townsend, 1901). The data collected at 
these stations consisted of temperature and 
density determinations, the latter being made 
with a hydrometer. The results of the expedi- 
tion (not previously published in this form) 
are shown in Figure 3. 
