I02 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



of Todos Santos it expands to the 40-fathom curve. Point 

 Banda lies 12 miles N. NW. from Point Santo Tomas. 



In latitude 31^ 55' a third broad but not important sub- 

 merged valley points to the east, just north of Point San 

 Miguel, and forms part of San Miguel Bay. 



It is to be noted of these three submerged valleys that the 

 100 and 200-fathom curves follow generally the conforma- 

 tion of the coast, which is quite high and precipitous, and 

 reaches 3,347 feet elevation in two and three-fourths miles. 

 The exception to this characteristic coast-line is in the south- 

 eastern part of the Todos Santos Bay, which is the low 

 opening of a broad valley draining to the northwest. This 

 low shore and valley decrease in width inland. 



The Submerged Valley of Descanso Bay. 



There is clearly indicated a submarine ridge running 

 northwest and southeast through the Coronados Islands, 

 about seven or eight miles offshore and parallel with it. 

 It reaches from latitude 32° 03' to the Coronados, latitude 

 32° 41'. Inside of the southern point of this ridge, 7^ 

 miles off Point Sal si Puedes, and carrying from 15 to 

 60 fathoms of water, there enters from the southward a 

 broad valley, two to five miles wide, with 425 fathoms. It 

 reaches 50 fathoms ten miles to the northward, under Point 

 Descanso. 



The soundings show green mud at two points north and 

 south in this valley; land and shells on the outer ridge in 

 30 to 60 fathoms. Three and a half miles outside the 100 

 fathom plateau, in latitude 32° 18', the depth reaches 773 

 fathoms. 



6. The Submerged Valley of Los Coronados Islands. 



This is a deep, sharp valley penetrating the northern part 

 of the San Diego or Coronado plateau from a depth of 622 

 fathoms to 50 fathoms in seven miles. Its general direction 



