398 Scientific Intelligence. 



County, Harry Foster Baine; Some Niagara Lime-Burning 

 Dolomites and Dolomitic Building Stones of Iowa, Gilbert L. 

 Houser. 



In discussing the classification of the geological formations of 

 Iowa, Mr. Keyes has availed himself of the results of his own 

 studies and those of others in recent years, and offers a classifica- 

 tion that is a marked advance on those preceding it. With 

 respect to Iowa's geological puzzle, the Sioux quartzite, some 

 additional facts are noted which are presented in greater detail, 

 however, in Mr. Beyer's paper. These relate to the discovery in 

 a deep well at Hull, Iowa, of typical quartz-porphyry, an erup- 

 tive rock, in layers separated by beds of sand and pebbles pre- 

 sumably belonging to the Sioux quartzite. Reference is also made 

 to the observations of Culver and Hobbs, showing the presence 

 of intrusive sheets of eruptive rock within the quartzite in south- 

 eastern Dakota. The most probable explanation of the presence 

 of the eruptive rock advanced by Mr. Beyer is that the sheets 

 were intrusive lava flows from a post-carboniferous volcano. 

 Considering the metamorphosing effect of eruptive rock it is to 

 be questioned whether these rocks are as old as usually consid- 

 ered and Hayden's conclusion that they were Cretaceous is in- 

 vested with new interest. We note the absence of such familiar 

 names as Lower Magnesian, Potsdam, and Hamilton. The first 

 is replaced by McG-ee's Oneota, the second by Winchell's St. 

 Croix, while the attempt to correlate the Iowa Devonian with the 

 New York section is wisely abandoned, and instead we have four 

 sub-divisions, named from the place of their best development, 

 the Independence Shales, the Cedar Valley Limestone, the Mont- 

 pelier Sandstone, and the Lime Creek Shales. In defining the 

 St. Louis group, on page 12, an error occurs in stating that the 

 brecciated limestone is the basal member. Ten to twenty feet of 

 magnesian limestone lie below this along the Des Moines river. 

 The interesting and valuable discussion is given of the structure 

 of the coal measures. 



In Prof. Calvin's paper the Cretaceous deposits are shown to 

 belong to the upper division and have a three-fold division cor- 

 responding to Meek and Hayden's Niobrara, Ft. Benton and 

 Dakota. Much taste and care is shown in the make-up of the 

 volume and the illustrations are exceptionally good. Acknowl- 

 edgment should have been made to the Missouri Survey for 

 the photograph for plate IX, as it was obtained by the writer 

 while a member of that survey. c. h. g. 



2. Note upon some observations o?i the auriferous Gravel of 

 lacustral origin in the region of Taylor sville, California y by 

 J. S. Diller (from a letter to the editors, dated Aug. 28). — 

 Recent observations show that to the southward the limit of the 

 exposed area of lacustral gravels is the old shore line which has 

 been much obscured by subsequent erosion ; to the northward the 

 gravels pass beneath the newer lavas of the Lassen Peak region 

 and may extend far in that direction. Within, the area is chiefly oc- 



