342 The Americaft Geologist. December, \m* 
construction by waves. But to omit altogether the agency of 
waves seems error, in view of the field evidence afforded on 
lake and ocean shores alike, that waves have done practically 
all the work on some forelands, and have had a large share in 
a far greater number of others than has been believed by 
certain students of the subject. 
Plate XVI. 
Fig. I. Blunted cusp, north shore of St. Patrick channel, three and 
one-fourth miles east of Whycocomagh. The southeast edge of the la- 
goon is a steep face, one foot high. 
Fig. 2. Blunted cusp, one-fourth mile west of fig. i; length, about 
seventv-five feet. 
THE STONE REEF AT THE MOUTH OF RIO 
GRANDE DO NORTE, BRAZIL. 
By J. C. Brannek and C. E. Gilman. 
Any person unacquainted with the stone reefs of Brazil, 
and seeing the one at Rio Grande do Norte, would find it 
difficult to believe that it was not a work of art. It stands 
like a long, low and nearly straight wall across the mouth of 
that river. Its total length is almost three miles, and in 
width it varies from 75 to 250 feet. It is barely covered by 
the highest tides. At its southern end it abuts against high 
cliffs; at its northern end it is cut off by the bar or entrance 
to the river and to the city of Natal. An old fort, within 
which is a lighthouse, stands upon the reef about two 
thousand feet south of the bar and nearly two miles from the 
southern end of the reef. 
From the fort to its northern end at the bar the reef has 
deep water on both sides of it, but south of the fort it has 
sand dunes close to it with shallow pools of water from lOO 
to 600 feet wide between the reef and their sandy shore at 
high tide. 
The surface of the reef has a gentle slope toward the 
ocean. This surface is etched and eroded in a peculiar man- 
ner. In places small flat pieces, a foot or two in diameter, 
are supported on a single leg like so many toad stools or 
