356 Prof. Hartt on the Brazilian Sandstone Reefs. [June, 
If a beach be growing rapidly, or if it is being rapidly worn 
away, solidification cannot take place, because it is only overa 
stationary shore, that is neither receiving new accumulations of 
sand nor parting with its old, that enough time is granted for the 
accomplishment of this result. Therefore, consolidated beaches 
must be the exception and not the rule on the Brazilian coast, 
where the shore is undergoing much change nearly everywhere, 
and as sandstone reefs seem to be confined to that single country, 
it must be that there alone are the proper conditions attained for 
their formation. The hardening appears to extend from the outer 
side of the beach inwards, and from below upwards, as new reefs 
usually lie on the lower and outer part of the beach; the younger 
reefs are also softer in texture than the older, more-finished ones. 
It is probable that many of the ordinary Brazilian beaches are 
solidified below the surface, but until something happens to 
uncover them, it is impossible to determine the fact. Reefs in 
process of formation are to be seen on the coasts of both Per- 
nambuco and Bahia, and at Porto Seguro; in the latter province, 
there is a double reef, the outer one being the wreck of an‘unfin- 
ished structure, the inner still undergoing solidification. 
Prof. Hartt was led to believe, from his earlier studies of the 
Brazilian stone reefs, that a slight elevation of the land was ` 
necessary to account for their present position; but his later 
studies proved to him that such an hypothesis was wholly 
uncalled for, and that none of the reefs reach above high tide 
level, or at the most above the level to which a beach is saturated 
with water at high tide. 
Statements have been published that a certain amount of 
upheaval must have occurred to produce the supposed strong 
seaward dip of the laminz of the sandstone; but nowhere, 
excepting on edges where blocks have been undermined and 
tilted up, is the inclination greater than might obtain on a sand- 
ach. To suppose an upheaval to have effected these narrow 
lines of reef, tilting the strata evenly in one direction, and no part 
of the neighboring coast, is a geological absurdity. The reefs 
follow the general trend of the shore, and are more or less 
curved, but.generally straighter than the beaches immediately 
back of them. 
Having shown that the curious reef at Pernambuco, which for 
many years was a complete puzzle to explorers, has been formed 
tee the agency of very Anite forces, in part working upon 
