276 F. W. SARDESOX A CORROSION CONGLOMERATE 



storms or bv sea-currents — a sort of sargasso — would appear to be a suf- 

 ficiently powerful agent to tear up the bed of shallow sea, at least under 

 favorable conditions, over verj' wide areas. Earthquakes might be the 

 direct cause of loosened stone on the sea-bottom; or, again, of currents 

 such as to cause dragging up of the bottom by sea-weeds, C. D. Walcott^ 

 mentions ice as a possible cause of Paleozoic intraformational conglom- 

 erate. Folding or faulting of the sea-bed, as it appears to me, might 

 raise and expose an area to sea-current and thus prevent deposition for 

 a time, and allow corrosion conglomerate to form, without the sea-bottom 

 anywhere rising above sealevel. Since the conglomerates are found in 

 limited horizons instead of throughout the beds or formations, their 

 origin is to be attributed rather to catastrophies such as rafts of sea- 

 weeds, etcetera, than to mere exposure of the sea-bottom by cessation of 

 sedimentary deposit or to other general cause. The agents and circum- 

 stances just mentioned would further indicate shallow sea as the place 

 where corrosion conglomerate formed. Its place of origin lies, therefore, 

 more or less closely to the seashore or to where beach gravels might be 

 forming. The significance of shore-erosion conglomerate and of corro- 

 sion conglomerate in regard to the place or depth of sea indicated by the 

 one or the other is not widely different. There- is a much greater differ- 

 ence with respect to permanence of the sea. If intraformational or other 

 conglomerate that extends 50 or 100 miles wide is interpreted as ero- 

 sional, it means that the sea once retreated and, of course, readvanced its 

 shore across that entire area ; while if the conglomerate is interpreted as 

 corrosional, it means a quiescent period, at least as to retreat and read.- 

 vance of the sea. 



9 Loc. cit. 



