358 The American Geologist. December, i896 
ner in which the research has been divided, certain special 
phenomena have had undue influence upon the results. 
Authors have based the classifications in a one-sided manner 
upon the lithologic characters, and, since local alterations in 
the rock often exceed the original differences, mistakes have 
resulted. 
Neither the Maquoketa nor the Galena series consists wholly 
of limestone except locally. The Galena series is limestone 
in its southern (Illinois) extent, but towards the north it in- 
cludes shales and clays. The Maquoketa series is mainly 
limestone and dolomite in the north (Minnesota) but becomes 
gradually shale and clay southward. Both together consist, 
nevertheless, of a series of beds that are divided from one an- 
other by lithologic and paleontologic dilFerences. Very natu- 
ral division lines obtain, and some of these have been chosen 
by authors in every ease as the limits for the formations and 
beds they have deemed worthy of designation, but, unfortu- 
nately, not everywhere have they chosen the same. Even 
where the intention has been to maintain a prior classification 
the divisional zones have been mistaken, because, owing to 
both original differences and local alterations of lithologic 
characters, the same beds are not everywhere alike nor sepa- 
rated by like contrasts. 
A brief outline of the divisions and the names of them, ac- 
cording to different classifications in each state is shown in the 
following diagram; but there is omitted from it the (;lassiflca- 
tion by N. H. Winchell and E. O. Ulrich* which is essentially 
a repetition of an earlier classitication that is included in this 
discussion. The " special designations" used in the same vol- 
ume are for the present omitted since their discussion would be 
very detailed and really unnecessary. Palpable errors are also 
not tabulated. 
Synonyrny of Terms. 
In the following tables of synonymy the older of the two 
series, the Galena, is given first, then its divisions and subdi- 
visions in the order of sequence, after which the Maquoketa 
series in like manner. 
*Geol. of Miun., final report, vol. 3, pt. 1, p. L. 
