Description:
This bulletin contains the principal data available as to the succession
of rocks in Arizona and the general structural features in most portions
of the State. It presents many new facts obtained in a reconnaissance of
various districts during 1919 to 1922 to obtain data for parts of the
Arizona Bureau of Mines geologic map of the State, and much material
compiled from various published reports. No attempt has been made to
utilize old material which, having been replaced by better data, is now
011lv of historic value. Details from published reports are omitted or gen-
eralized as far as possible, as persons interested in more extended descriptions
of stratigraphy or structure can consult the original sources of information
indicated by th'e footnote references. In districts where the
published data are meagre, or where they are here published for the first
time, more details are given.
Some descriptions of local geology are incomplete because of lack of
knowledge.
The bulletin consists of two parts: The first, a resume of the characteristics
of the various formations, with all available new light on their classification;
and the second, brief descriptions of many districts, mountains,
plateaus, and other features, arranged under counties.