INDEPENDENCE SHALE NEAR BRANDON 491 



die usual opinion that the Lime Creek fauna is a greatly expanded 

 and recurrent descendant of the Independence rather than a contem- 

 porary; (3) the brecciation of the lower Devonian terranes of Iowa 

 has had a profound effect on their structure. Minor folds, flexures, 

 distortion, obscured bedding, small faults with throws from a few 

 inches to a score of feet or more, together with the cracking and 

 breaking of the rock into angular fragments of all sizes are some of 

 the features resulting from the stresses to which these terranes were 

 subjected. The shaly portions of the Independence beds being plas- 

 tic and incompetent under the strain were evidently squeezed up 

 into crevices, pipes, and under arches. At exposures Nos. 1 and 2 

 the limestones are considerably flexured, broken and displaced. All 

 along Lime creek in the vicinity of Brandon "the beds are folded, 

 buckled and displaced on a scale sufficient to produce a complex se- 

 ries of alternations of lithological and paleontological characters at 

 the same level along the hillside."^*' The prominent fault near ex- 

 posure No. 3, the angular blocks of Lower Davenport and Otis lime- 

 stones mixed throughout the shale at each exposure, the lack of bed- 

 ding and continuity, and their anomalous position abutting against 

 Cedar Valley limestones, all point to the reasonable conclusion that 

 the shales have been forced up into their present position at the 

 Brandon exposures by the forces which produced the brecciation. 

 It is not urged from this that the shales have everywhere been so 

 squeezed out of their natural position, in fact Calvin^^ calls atten- 

 tion to the point that the overlying Gyroceras beds at Kildufif's 

 quarry are undisturbed and it is inferred from his note that the 

 shales below, at this place, are also stratified and "alternating with 

 beds of limestone" as quoted earlier in this paper. 



In closing the writer wishes to acknowledge the valuable sugges- 

 tions of Dr. William H. Norton with whom the outcrops were 

 studied in the field. The conclusions arrived at are a result of this 

 conference and to Doctor Norton, whose critical study of the brec- 

 ciation of the Iowa Devonian is well known, should be given spe- 

 cial credit for the suggestion that the present position of the shale 

 at each outcrop is a result of the squeezing accompanying breccia- 

 tion. 



The Department of Geology, 

 The State University. 



"Calvin, Iowa Geol. Surv. Vol. VIII, 1898, p. 238. 

 "Amer. Geol., Vol. IX, 1892, p. 359. 



