326 The Cincinnati Rocks. — Perry. 
by those for whom they were written. And his conservatism 
kept him from hasty and glittering generalities and from the 
corrections and retractions incidental to undue haste and 
excessive personal ambition. 
One volume of the final report had appeared and a second 
one was about ready to be sent to press at the time of his 
death. His plan contemplated its publication in four volumes, 
including a summary of the geology of the state and a report 
on the paheontology. 
Dr. Cook was honored by membership in many societies. 
At the Cleveland meeting of the American Association he gave 
the vice-presidential address in Section E. In 1887 he was 
elected a member of the National Academy of Science. Of the 
International Geological Congress he was an active member 
and the reporter of the Mesozoic. From the University of 
New York he had received the degree of Ph. D. as early as 
1856, and Union College had honored him with that of doctor 
of laws. 
A friend whose devotion never wavered, a loyal citizen, 
ready for every duty, a true scientist and a manly Christian, 
he has. left an example for Us, if we would make the world 
better and wiser. 
THE CINCINNATI ROCKS: WHAT HAS BEEN THEIR 
PHYSICAL HISTORY? 
By Nelson W. Perry. 
The group of rocks forming the upper portion of the Lower 
Silurian, and more specifically known as the "Cincinnati 
group," has been for many years one of the most interesting 
to the paleontologist and geologist. The great abundance 
and variety of its fossils have attracted the attention and study 
of specialists in all parts of the world, and the result is that 
its life history is now pretty well understood. The physical 
history of this group, however, has been but little studied, 
and even to-day we find but little in literature bearing on this 
subject. 
The problems presented are of a peculiar nature and seem 
not to be duplicated in any other of the great geological 
epochs — certainly not on such a grand scale. This fact has 
not until recently been duly recognized. Tlie phenomena 
