394 Tertiary Formations. part n. 



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not represented steep enough, for I particularly noticed 

 that before the beds had been tilted to the right, this 

 line must have been nearly vertical. It appears that a 

 current of water cut for itself a deep and steep sub- 

 marine channel, and at the same time or afterwards 

 filled it up with the tufaceous and brecciolated matter, 

 and spread the same over the surrounding submarine 

 beds; the matter becoming stratified in these more 

 distant and less troubled parts, and being moreover 

 subsequently covered up by other strata (like A A) not 

 shown in the diagram. It is singular that three of the 

 beds (of A A) are prolonged in their proper direction, 

 as represented, beyond the line of junction into the 

 white tufaceous matter : the prolonged portions of two 

 of the beds are rounded ; in the third, ' the terminal 

 fragment has been pushed upwards : how these beds 

 could have been left thus prolonged, I will not pretend 

 to explain. In another section on the opposite side of 

 a promontory, there was at the foot of this same line 

 of junction, that is at the bottom of the old submarine 

 channel, a pile of fragments of the strata (A A), with 

 their interstices filled up with the white tufaceous 

 matter : this is exactly what might have been antici- 

 pated under such circumstances. 



The various tufaceous and other beds at this northern 

 end of Chiloe probably belong to about the same age 

 with those near Castro, and they contain, as there, many 

 fragments of black lignite and of silicified and pyritous 

 wood, often embedded close together. Thev also con- 

 tain many and singular concretions : some are of hard 

 calcareous sandstone, in which it would appear that 

 broken volcanic crystals and scales of mica have been 

 better preserved (as in the case of the organic remains 

 near Castro) than in the surrounding mass. Other 

 concretions in the white brecciola, are of a hard fer- 



