C. A. Reeds — II union Formation of Oklahoma. 265 



which is here represented. It may yet he determined that the 

 uppermost 40 feet of the Bois d'Arc are Oriskany in age. 



Lifhology. — The Bois d'Arc limestone consists of thin 

 hedded crystalline and non-crystalline limestone with occa- 

 sional chert lentils and thin beds of intercalated yellowish 

 shale. In the Coal creek and Goose creek sections a 6-foot 

 bed of yellowish shale occurs near the middle of the formation. 

 "Where the crystalline ledges have weathered considerably the 

 rock is readily worked for fossils, but the non-crystalline lime- 

 stone instead is very hard and weathers into thin lenticular 

 lenses. 



Fauna. — The fossils indicate that for most places in the 

 Arbuckles deposition was continuous from the Haragan shale 

 into the Bois d'Arc limestone. The contacts, however, are 

 sharp where the beds are gently inclined, but not always so 

 where the beds are steeply tilted. This is due to the less effect- 

 ive power of the agents of weathering. In passing from the 

 Haragan shale to the Bois d'Arc limestone, thin intercalated 

 shale beds are to be found between the ledges of limestone in 

 the lowermost 5 feet of the Bois d'Arc limestone. This is 

 well illustrated in the thick sections across the Dougherty anti- 

 cline and along Haragan creek. In the type area in the north- 

 east corner of the mountains the Bois d'Arc limestone rests 

 unconformably on the Henryhouse shale, for strangely enough 

 the Haragan shale is not represented here. This suggests that 

 the northeast corner of the Arbuckle Mountains was above sea 

 level during Haragan times, and possibly that the Henryhouse 

 was not affected much by erosion since the thickest section con- 

 taining the highest horizon of the formation occurs a mile away 

 on Chimneyhill creek. Since deposition was continuous in 

 various places from the Haragan shale into the Bois d'Arc 

 limestone, it is not surprising that the lower part of this lime- 

 stone, in such places, has a New Scotland aspect. Since, how- 

 ever, there are a number of fossils that are characteristic of this 

 limestone it is best treated as a separate formation. It is more 

 nearly the Becraft than the New Scotland of the New York 

 section. The names of the fossils which are peculiar to this 

 formation are as follows : — 



Characteristic Species op the Bois d'Arc Limestone 

 (Devonian). 



Dendropora n. sp., Favosites shriveri, Trachypora n. sp., 

 Pisoerinus sp., Codaster n. sp., Cyrtina rostrata, Eatonia 

 singularis, leptostrophia magnifica, Leptostrophia oriskania, 

 3Ieristella Icevis, Meristella lentiformis, Rensselceria mary- 

 landica, Spirifer concinna, SSpirifer cyclopterm, cf. hartleii, 



