9-1 NEW YORK STATE MUSEUM 



wliolly or in large part of lime. Thus we have lime rubble rocks 

 represented in this region largely by limestones carrying worn 

 fragments of corals, lime sandrocks, well represented by lime- 

 stones composed of ground-up but not pulverized shells, crinoids^ 

 corals etc. ; and lime mudrocks composed of the limestone flour, 

 deposited in quiet water, and having a compact texture, where 

 individual grains are not recognizable. This latter type of rock 

 is well represented by the waterlimes and other close textured 

 limestones of the Schoharie region. When the shore from which 

 clixj or silica is derived is near enough, impurities of these sub- 

 stances may become admixed with the lime, thus producing: 

 argillaceous or silicious lime mudrocks, etc.^ 



From the foregoing it becomes apparent that fragmental rocks 

 of varying texture and composition will be deposited at the same 

 time, in different parts of the ocean. Furthermore the same bed 

 may change in texture and composition Avithin a comparatively 

 short distance. Thus a quartz conglomerate at the shore will 

 grade into a quartz sandrock away from the shore, and if coral 

 reefs or shell heaps are growing off the shore, it will gradually 

 grade into a calcareous quartz sandrock (calciferous sandrock) 

 then a silicious lime mudrock (silicious limerock) and finally a 

 mor-e or less pure lime sandrock or lime mudrock. In section such 

 a bed would be thin at the shore where the water is shallow, 

 rapidly thickening seaward till the maximum is reached, and then 

 thinning away gradually in the deeper water as the material 

 becomes finer, and accumulation therefore slower. 



Three lines of activity may be considered in a normal seashore 

 where deposits of this type are forming. First, the sea level may 



^Tbe author has recently proposed the terms riidaceous, arenaceous and 

 lutaceous for rubbly, sandy and muddy textures respectively. For clastic 

 rocks of this texture, irrespective of composition, the terms rudyte, arenyte 

 and lutyte have been proposed. Where the composition is pure the 

 chemical name may be added. Thus lime mudrocks are calcilutytes, lime 

 sandrocks are calcarenytes and lime rubblerocks calcirudytes. See further 

 Geol. Soc. Am. Bui. 14 : 337 and Am. Geol. 33 : 228. 



