22(5 Reviews — Water Resources of Iowa, U.S.A. 



Tlie general geology presents many points of interest and is 

 illustrated by coloured geological maps and pictorial views; t)iere is 

 also a map of Central Alaska, showing the position of the coal-fields. 



VI. — Underground Water Resoueces of Iowa. 



ri^HE twenty-first volume of the Iowa Geological Survey contains 

 jL the Annual Reports for 1910 and 1911, with statistics of the 

 Mineral Production of the State for 1909 and 1910 ; but it is occupied 

 mainly by a connected series of reports on the Underground Water 

 Resources, The result, a huge quarto volume of xvi + 1214 pages, 

 lias been issued under the direction of Mr. George F. Kay, the State 

 Geologist. The investigation of the water-supply was initiated by 

 the late Samuel Calvin, and since 1903 it has been carried on in co- 

 operation with the United States Geological Survey. 



The artesian waters have been studied in particular by Mr. W. H. 

 Norton (geologist for underground waters) ; the waters of the Drift 

 and Countrj' Rock, or the ground waters, are dealt with by 

 Messrs. Howard E. Simpson and 0. E. Meinzer, and their chemical 

 and industrial qualities are discussed by Professor W. S. Hendrixson. 

 Here it may be mentioned that the term ' coixntry rock ' is applied 

 to " the rock which outcrops at the surface or immediately underlies 

 the drift" ; Avhile the term ' aquifers ' is given to the ' water-beds ', 

 or, as we should call them, the water-bearing strata. 



The artesian aquifers are mostly deep-seated and of early Palaeozoic 

 age, but the strata naturally approach and come to the surface in 

 places, where they might be included in the country rocks. 



Iowa State is divided into ninety-nine counties, aud fortunately 

 the Geological Survey, having very nearly completed the field-work 

 of the entire area, had also accumulated much information relating 

 to the geologic conditions which control the ground water. Furtlier 

 particulars, as full as possible, have now been gathered from the 

 officials of each town and from well-drillers in connexion with the 

 underground water-supply. It is justly remarked that with regard 

 to the artesian waters "there is needed the skillful interpretation 

 of data collected from a wide area, a knowledge of the geological 

 structure and acquaintance with the distribution and movements of 

 deep waters", as " the local well driller cannot be expected to know 

 either the quantity or quality of artesian waters or the depth at 

 which they can be reached ". 



Many useful hints are given on the collection and preservation 

 of samples from borings, on the errors that may arise in the 

 determination of the nature and thickness of the rocks by means 

 of drillings and the contents of slush-buckets, the difficulty and 

 rarity of getting precise palaeontological evidence, and of the local 

 experience necessary in determining the age of formations by litho- 

 logical evidence. 



These and other matters are discussed by Mr. Norton in an Intro- 

 duction to the general account of the Underground Water Resources. 

 The Topography and Climate are dealt Avith by Mr. Simpson ; the 

 Geology \>j Messrs. Norton and Simpson, wlio give a iiseful table of 



