340 A. W. GRABAU — PALEOZOIC CORAL REEFS 



uniformly grained fragmental lime sandstone (calcarenite ; see postea), or 

 consolidated coral sand, with occasional beds composed wholly of crinoid 

 fragments. Fine grained beds of lime-mud sand (calcilutiie) are also 

 found. At intervals the section passes near enough to the reef to show 

 the presence of numerous coral fragments. The fragments are all much 

 worn and broken, and are embedded as boulders or pebbles in the strati- 

 fied lime sands. Where they are abundant they constitute a veritable 

 coral conglomerate (calcirudite) such as may be found near the borders 

 of modern reefs. Good exposures of such conglomeratic beds are found 

 in the quarries and shore sections east of Petoskey, where these coral 

 pebbles (chiefly Acervularia and Favosites and the hydrocoralline Stro- 

 matopora) give the rock a strikingly mottled appearance. Not infre- 

 quently seams of carbonaceous material separate some of the layers of 

 limestone, and in these plant remains are not uncommon. Within the 

 thicker beds themselves the phenomena of contemporaneous erosion, of 

 the wedging out of strata, and, occasionally, of cross-bedding and ripple 

 marks are met with. Indeed, all the phenomena seen in heavy bedded 

 sandstones are found in these fragmental deposits. 



ONONDAGA BEEF OF WILLIA3ISVILLE, NEW YORK 



The Jones lime quarries of Williamsville, New York, are opened on 

 the flanks of a coral reef, in the inface of the Onondaga cuesta. The 

 reef itself is exposed only in the floor of the old quarry on the w^estern 

 flank of the dome. Here in the south wall the beds have a general dip 

 of from 5 to 10 degrees westward, and a similar one, in the east and west 

 walls, to the north. These dips indicate that the quarr}^ is situated on 

 the northwest quarter of the dome. In the new, or eastern, of the two 

 quarries the dip is eastward and northward, while a southward dip is 

 also found in one portion of the quarry. This one, therefore, is opened 

 in portions of both the northeast and the southeast quarters of the 

 dome. It is also opened at a greater distance from the center of the 

 reef, no portion of this being actuall}^ exposed in the quarr3^ The north 

 and south extending walls of the quarries farthest removed from the reef 

 show horizontal bedding, because the dip in these is at right angles to 

 the wall — that is, either east or west; w^hile the walls nearest the reef 

 show the north and south dips. Corals are most abundant in the 

 western portion of the eastern, and in the eastern portion of the western 

 quarry — that is, nearest to the reef in each case; while away from the 

 reef the rock becomes a regularl}' bedded consolidated coral and crinoid 

 sand. The floor of the western quarry near the reef consists of a mass 

 of cemented coral heads, among which Favosites, Diphyphjdlum, Syrin- 

 gopora, Cyathophyllum, and Cystiphyllum })redominate. Crinoid stems 



