ENDOGENETIC SANDS 283 



Spherytes, Granulytes, and Pulverytes (pelytes). These 

 names have heen suggested (Grabau-io) for rocks composed of 

 aggregates of constructional origin' simulating in texture destruc- 

 tional or clastic rocks and having many features in common with 

 them, such as stratification, etc. The textures which characterize 

 these rocks are sphcrytic, granulytic, and puherytic, corresponding 

 to the textures rudaceous, arenaceous, and lutaceous among the clas- 

 tic rocks. Thus a rock formed of volcanic bombs would be a 

 splicrytc, one formed of lapilli or oolitic grains a granulyte, and one 

 formed of diatom frustules, or minute radiolaria or foraminifera, a 

 pnlvcrxtc. The last three types would be of biogenic origin, and 

 therefore would constitute hiopulverytes, two of them being bio- 

 silicipulverytes, the material being silica, the third a biocalci- 

 pulveryte, the material being calcite. A pulverytic rock of hydro- 

 genic origin would be a hydropulveryte. As suggested above, the 

 term pelyte (from the Greek 7ri;Xds, slime) might well be restricted 

 to muds and slimes of endogenetic origin, and so be used instead 

 of the word pulveryte. Thus, instead of pyro-, atmo-, hydro-, and 

 hiopulverytes, we may use the terms, pyropelytes, atmopelytes, hy- 

 dropelytes, and biopelytes. 



Chemically formed oolites are hydrocalcigranulytes, or, if of 

 silica, hydrosilicigranulytes. The oolitic iron ores of Wisconsin 

 (Siluric) are probably hydroferrogranulytes. Organically formed 

 ooHtes are biocalcigranulytes ; granular snow (firn) is an atmo- 

 granulyte, and volcanic lapilli form a pyrogranulyte. A bed of vol- 

 canic bombs is a pyrospheryte, and one of unworn coral or Girva- 

 nella heads a biospheryte (biocalcispheryte). All of these rocks are 

 of endogenetic or nonclastic origin. 



OOLITIIS, PiSOLITHS, RoGENSTEINE, ETC. Rocks COmpOSCd of 



spherical grains of either hydrogenic or biogenic origin are called 

 Oolites or Ooliths when the grains are small, and Pisolites or 

 Pisoliths (Pea grits) when they have the size of a pea or over. 

 Rogensteine are ooliths or pisoliths in which the grains (ooids) 

 are held together by a more or less argillaceous cement. In typical 

 ooliths, so named from their resemblance to fish-roe, each grain 

 consists of successive concentric shells of carbonate of lime, and has, 

 moreover, commonly an internal radiating fibrous structure, which 

 gives a black cross between crossed nicols. The lime is often de- 

 posited around some foreign Ijody, but also often without such a 

 body, forming a sphere hollow at the center. The granules consist 

 ^ sometimes of aragonite. sometimes of calcite, or they are formed 

 by an intermediate substance, ktypeit. Great variation in size occurs. 



