Febeuaby 20, 1903.] 



SCIENCE. 



291 



A. "W. Grabau mentioned that the pro- 

 gressive overlap could be carried farther 

 even up into the Silurian ; and also that in 

 New York we have in the Niagara lime- 

 stone a formation whose time equivalent 

 ought to be a sandstone in Ontario. N. 

 H. Winchell carried the idea still farther in 

 that in Minnesota the Cretaceous rests on 

 the Archean, and stated that the break 

 might be traced even to the present. Dr. 

 Ami, in reply, stated that he used the term 

 'Eparchean Formation' in a purely strati- 

 graphic sense with the purpose of em- 

 phasizing the first sandstone deposits found 

 in various places in the East. 



The Basal Conglomerate in Lehigh and 



Northampton Counties, Penn.: Pked- 



EEicK B. Peck, Easton, Pa. 



The basal conglomerate occurs here as 

 elsewhere, fringing the Precambrian areas. 

 In eastern Northampton County it fails oc- 

 casionally, (1) as a result of faulting or 

 (2) because it was never deposited. It 

 has a thickness varying from zero at Eas- 

 ton, to one hundred or possibly several hun- 

 dred feet at Alburtis, twenty-four miles 

 southwest of Easton. 



Petrographically, it is quite variable. 

 At times it is a coarse conglomerate, made 

 up of quartz pebbles an inch or two in 

 diameter. Frequently it is a medium to 

 fine-grained arkose, consisting of about one 

 part feldspar (orthoclase and microcline) to 

 two or three parts quartz, the former us- 

 ually thoroughly kaolinized, the latter 

 badly crushed, and under the microscope 

 exhibiting an undulatory extinction, and 

 occasionally a distinctly biaxial character. 

 Other phases of it present a dense bluish 

 or grayish quartzite. It occasionally con- 

 tains interstratified beds of a very fine- 

 grained, argillaceous sandstone with nu- 

 merous worm borings (Scolithus), but 



as yet no distinctively lower Cambrian 

 fossils have been found. The seemingly 

 uppermost member is a highly ferruginous, 

 almost jaspery quartzite, which locally con- 

 tains iron enough to constitute a low grade 

 ore. From this horizon a considerable 

 amount of iron ore was formerly derived. 



In discussion Bailey Willis remarked the 

 difficulty of tracing the break between the 

 ancient crystallines and the lowest sedi- 

 ments when the latter consist of the weath- 

 ered debris of the former, deposited near 

 their source. If, however, the lowest beds 

 are sandstones, such as now form the 

 beaches along the Atlantic, they represent 

 the residues, which have been repeatedly 

 worked over by the sea, and have no neces- 

 sary relations to the neighboring crystal- 

 lines. 



Dr. Peck replied that, in his area, they 

 seemed to represent the products of secular 

 decay, and to have been deposited near 

 their source. 



The Sandstones of the Ozark Region in 



Missouri: Curtis F. ]\Iaebut, Columbia, 



Mo. 



The author first gave a short sketch of 

 the history of geological investigation in 

 the region, with reference chiefly to the 

 various classifications which have been pro- 

 posed for the rocks of the Ozark series. 

 The older geologists made out four lime- 

 stones and three sandstones. F. L. Nason 

 had supported the view that there were two 

 limestones and one sandstone. By means 

 of maps the speaker described the evidence 

 which had led him to the conclusion that 

 there are certainly two, and there may be 

 three or even four, sandstones. 



Dr. Purdue remarked in discussion that 

 there are in Arkansas at this horizon heavy 

 sandstones and limestones, seven in number, 

 which shade into each other. 



