296 Th6 American Geologist. November, 1001. 
where, of all bights and dimensions." * * * "They do 
not coalesce here as elsewhere, to form large reefs as they do to 
the west of the islands." 
Professor James D. Dana says of their structure : "The 
rock of these submerged coral-heads is but a loose aggregation 
of coral in the position of growth, except possibly, in their low- 
er portion, where the open spaces may be filled with sand and 
fragments cemented together." 
SIMILAR OCCURRENCES IN OTHER GEOLOGIC HORIZONS. 
Lock port (A-iagara) Limestone: — At Niagara gorge, about 
one-half mile above (south of) the suspension bridge and one 
hundred yards north of where the Gorge railway reaches the 
open face of the ledge beside the track, and at a level twenty or 
twent3'-five feet above the base of the Lockport limestone, is a 
reef [PI. xxx, Fig. 8] one hundred ten feet in length and ex- 
posed to the hight of twelve feet. It lies in a thin-layered strat- 
um of limestone separating two massive benches. The irregu- 
lar structure of the reef is in contrast to the thin-layered lime- 
stone, while the upper massive bench is arched over it. The 
reef rock is a compac'c bluish dolomite, weathering to a yellow- 
ish hue. Bryozoans are abundant, often in masses of consider- 
able size ; but owing to the comparatively recent date of the 
railway cutting weathering has done little to bring out other 
organic contents. It is probable that this mass originated in 
the same manner as those of the Clinton upper limestone. 
Other reef masses are conspicuous at this level along the 
gorge. One seen just north of the eastern end of the cantilever 
bridge is two or three hundred feet long. 
Seventeen miles eastward along the Niagara escarpment 
and three miles west of Lockport, in a road-cutting, three well 
weathered masses are exposed at the same level. [PI. xxxi. 
Fig. 9]. The first thing that arrests the eye is the loose struc- 
ture of these masses, strongly contrasted with the firm beds of 
inclusion. This, coupled with the remarkable assemblage of 
Niagara forms of bryozoans, corals, crinoids, brachiopods and 
other types, in a better state of preservation than the organic 
materials comprising the limestone of enclosure, favors the con- 
clusion stated, that here we have another example of reefs. 
•Coral and Coral islands, 1872, p. 142. 
