^NU The America II (ieoUxjist. November, 1«95 
foriijs dome shaped knolls covered with rounded i'ragiiients. 
The fossil l^eufa inents seems to be entirely wanting in the 
Coralline beds. In the American Geologist for August, 1893, 
<'alvin has mentioned some of the principal fossils of this 
horizon. They include FiiichophnUiDn e.rpansinn Owen, Sfroin- 
bodes (//(f(i.^- Owen, Pldsniopord astraforvu's Owen, and LyeT/id 
(/labvd Owen. In addition to these might be named Favosites 
nidcfd rcihsi.s Hall, /'. hispidus Rominger, F. hiio'iujeri E. & H., 
Si/riiif/opora verticelUita Goldfiiss, Zaphreiiti.s stokesi E. & H., 
Orfliis jidbellifes Hall, and several species of Alveolites and 
St rfiiiKifopovd . 
These upper Coralline beds are estimated at 40 to 60 feet 
in thickness. 
The beds that succeed the upper Coralline are the ones that 
have so often been described as the building stone of the Ni- 
agara. A good general description of these is quoted from 
McGee's writings, by C. R. Keyes in the Iowa report for 1892, 
page 31. They may be generally recognized by their very even 
bedding, butt' or bright yellow color, compact fine-grained tex- 
ture and the general absence of lustre due to crystallization. 
Chert laj'^ers are usually present, especially in the upper por- 
tion. Near Manchester these beds are of a decided blue or 
€ven jMirple color and nearly free from magnesium, but they 
are generally dolomitic elsewhere. The layers range in thickness 
from two or three inches, making rock adapted for flagging, 
to two feet or more. A system of joints trending about S. 70*^ 
E. is generally present. Very little seems to have been written 
about the fossils of these beds in Iowa and the fossils are less 
numerous than in the Pentamerus and upper Coralline beds. 
They comprise l^entanieriis oliJoiujiis Sowerby, Unronin verte- 
bvdtis Stokes, numerous species of Orttioceras, TU(('nus (Jayton- 
eiisis Hall and Whitfield, C'dJi/meiie nidf/arensis Hall, a few 
crinoids, Lituites and other coiled cephalopods. These build- 
ing stone beds are from 40 to 60 feet in thickness. 
Contacts between the Upper Silurian and Devonian rocks 
may be seen at Fa3"ette and on the banks of the river midwa^^ 
l)etween Coggon and Central City. In the last named place 
the rock lying immediately under the Devonian is a bulf, 
heavily bedded dolomite, barren of fossils and so little indu- 
rated that in places it can be easily dug with a spade. It 
