544 



Arnold Heitn — 



The Cuesta Formation is known as yet only from the region of 

 La Purisima, in a distance of 4 kilometres along the Arroyo 

 Cadegomo. Perhaps the immense mass of unfolded beds of 

 La Giganta Mountain, in its upper portion, contains the chronological 

 equivalents of the Cuesta Formation. 



No fossils have yet been found in the Cuesta Formation. Possibly 

 it is a continental facies of the Pliocene. 



N.W.-S.E. 



Mesa de La Salada. 



Arroyo de 

 La Salada 



Fig. 5. — The Salada Formation (Pliocene) of Kancho La Salada. A. Section 

 1,400 metres N.E. of ranch house. B. Section 1,000 metres N.E. of 

 ranch house. 1. Greenish soft sandstone, salty, apparently without 

 fossils ; rough and sharp contact toward 2. 0-3 m. gravel sand, con- 

 taining basalt pebbles and many badly preserved mollusks, Balanus, 

 Turritella, Chione, Chrysodomus, Calliostovia, Oliva, Comis, Tellina, 

 Bryozoa, and shark teeth. 3. 1 to 2 m. bank of rough sandstone with 

 shells of gastropodes and bivalves. 4. 0-5 m. greenish gravel sand, 

 passing gradually into 5. 4-1 m. soft sandstone, outside grey to violet, 

 inside greenish to bluish, containing pebbles of greenish miocene 

 shale. 6. 1-9 m. yellow gravel sand with plenty of mollusks, also 

 Balanus, Bryozoes. 7. 1-8 m. fine greenish shaly sandstone without 

 shells. 8. to 0-25 m. rough basalt conglomerate, incrusted with 

 white lime. 9. 2-0 m. grey nodular sandstone with plenty of mollusc 

 fragments, great Pecten at lower part ; passing gradually into 10. 1-5 m. 

 chalky breccious and porous limestone without shells. 11. Pleistocene 

 Mesa Conglomerate, formed chiefly of basaltic pebbles. 



Salada Formation (Pliocene). 



In the interior region of the Peninsula of Lower California 

 (Purisima-Comondii) the youngest known marine fossil beds are of 



