BRANNER: THE STONE REEFS OF BRAZIL. 161 
uncovered by the shifting of the currents. The coral reef surfaces are 
usually so blackened with corallines and other growths that the struc- 
ture cannot be seen, but at this place it is shown perfectly. Heads of 
Porites and other corals are cut through and partly eaten away either 
chemically or mechanically. At low tide these reefs are exposed for 
half a kilometre out seaward. Nearly one kilometre south of the beach 
exposure just mentioned is another place where the beach sands overlie 
a dead coral reef. The photograph given herewith was taken at the 
last-named place. It shows not only the in-shore reef but two other 
coral reefs further out : the further of these is nearly one kilometre from 
the shore, 
ў 
Е 
FF, 
7 
(Aker 
им & 
is р v 
ades: КЛ 
Fra. 89. High Rock, Maceio coral reef. From a photograph by Е. Ambler. 
Tn this connection mention should be made of a mass of coral rock on 
the reef at Maceio. The Maceio reef is of coral, is three kilometres or 
more in length, and varies in width from a few paces at certain points 
to nearly a kilometre at its northern end, where it joins the sandy beach. 
At one point east of Jaraguá a solitary mass of coral rock rises three 
metres above the general level of the coral reefs. There is no other 
such rock on the Maceio reefs, It was formerly supposed that this was 
the remnant of an old reef that had been cut away by the waves. The 
accompanying illustration made from a photograph kindly obtained for 
me by Mr. Е. Ambler of the Alagóas Railway Company at Maceio shows 
that this mass is simply a tilted fragment of the reef thrown into its 
present position by having been undermined at one еп. 
VOL, XLIV. ui 
