124 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 23, 



The fossiliferous sliale is well exposed in tlie deep cuttings of the 

 River Amiua at this place. The fossils are altogether disseminated. 



Fish teeth are frequently found upon the surface of the shale. 



Cercado (River Mao).— Beds of blue shale dip N.W. by N. 5°. 

 Fossils disseminated. 



This is merely the name of a locality where a few farm-houses are 

 built upon the banks of the river. 



A short mile southward from the houses, up the River Mao, the 

 blue shale is exceedingly well displayed in a cliff, 200 feet high from 

 the surface of the water, which may be termed the main cliff. 

 (Figs. 5, 6.) 



Fig. 5. — Section of the Cliff at Cercado, on the River Mao. 

 Height 200 feet. 



[The summit at A is about 900 feet above the sea-level.] 

 A 



'"'"■"^''~- ~ ._.~^--^ 5 



- ^"n-- - 4 



_i ^ ;_--^V 3 



/^ _ - ~ " ^ ' :".: ^^"',1 r— — —^^: "' "rbf: * I Level of the 



,„ , I River Mao. 



1 alus. 



Fig. 6. — Section of the Cercado Cliff, transvase to Fig. 5, at A, and 

 of the rising ground inland. 



■5 =« 



&,b5 



y Bluish sandy shales, fossiliferous. 



1. (10 feet exposed)^ 



2. 20 feet. 



3. 50 feet. 



4. 90 feet. Do., without fossils. 



5. 50 feet. ArfiUlo-calcareous shale, with fossils. 



6. from 10 to 20 feet, Coarse shingle. 



7. 300 feet, Tufaceous limestone. 



Dip 5°, N.W. by N. 



The shale is divided by partings or narrow bands, a few inches 

 thick; of more compact and hardened materials, which stand out in 

 strong relief along its nearly perpendicular front. Separate collec- 

 tions of fossils were made from the different beds. 



