CARBONIFEROUS LIMESTONES OF IOWA. 93 
No beds of coal have been discovered interlaminated with any of these groups. 
The lowest bed of coal observed lies fifteen or twenty feet above the upper surface 
of the highest member of this series. 
Subjoined is a table, contrasting the different groups that make up this series, 
with the beds composing the carboniferous limestone, as it occurs in Yorkshire, 
England, near Kettlewell and Great Whernside. Though the Yorkshire formation 
appears to be more than twice as thick as that of Iowa, a striking analogy may 
still be traced in their leading lithological features, particularly in the succession 
composing the upper part of the series, with its nodular and concretionary limestones 
at top and bottom. These speak of similar causes in operation during the period 
of deposition, in both formations, though they exist four thousand miles apart. It 
would seem that, after the deposition beneath the water of certain beds, and before 
complete consolidation, these were brought to the surface by slight oscillatory 
movements of the earth’s surface; that by the action of the sun and atmosphere 
their surface became cracked and fissured; and when again depressed, and the 
interstices filled with calcareous mud and argillaceous depositions, that the whole 
was re-cemented. 
TABLE EXHIBITING ANALOGY BETWEEN CARBONIFEROUS LIMESTONES OF 
YORKSHIRE AND IOWA. 
LIMESTONES BETWEEN KETTLEWELL AND GREAT UPPER LIMESTONE SERIES, NEAR THE MOUTH OF 
WHERNSIDE. THE DES MOINES. 
(Under grits and shales.) : (Under shales.) 
Limestone: a hard, sharp stone, in nodular beds. Limestone : compact, close-textured, brittle, white ; 
Limestone: a hard, sharp stone, in nodular beds. usually concretionary, with marly earth in the 
Parting of shale. interstices. 
Limestone: light-coloured. 
Parting of shale. 
Limestone: light-coloured. 
Parting of shale. 
Limestone: light-coloured. 
Plate. 
Limestone: rather dark-coloured, forming bold scars. 
Parting of shale. 
Limestone. 
Fine gritstone, occasionally yielding flags. Gritstones : brown and white. 
Gray limestones, with Producta in the lower beds. Limestone: compact, close-textured, brittle, white, 
Blue limestones, very solid, full of large Producta, _concretionary; containing Lithostrotion ; becom- 
Lithodendra, &e. ing more evenly bedded in its lower portion, and 
Red limestones, with Encrinites and Spirifers. containing Productus cora, P. Flemingi, Spiri- 
Gray limestone: in bold scars. fers, Terebratule, Melonites, Multipora, &c. 
Black nodular limestone. Sandstones : often with small pebbles. 
Gray limestone : small-grained, compact or splintery, 
white or : 
Various limestones : mostly compact, to the level of Magnesian limestones: buff, often cellular, or with 
Kettlewell-dale; including the “dun” (or mag- _ tubular perforations. 
nesian) limestone, full of ramifications, nodules, Limestones: impure, full of Geodes, containing cal- 
or hollow cells of calcareous spar. careous spar and quartz. 
