NORTHERN END OP THE HELDERBERG PLATEAU 69 



tion shows reticulated sun-cracks, and they 

 are also nicely displayed on the floor of the 

 quarry above the railroad track in its western 

 part. According to Charles O. Schaeffer 7 

 feet of the lower water lime is burned for 

 hydraulic cement, of which 5J feet is of first 

 quality. Mr Schaeffer furnished the follow- 

 ing analysis of a sample near the base. 

 Silica and insoluble matter 12.89 



Carbonate of lime 55.17 



Carbonate of magnesia 19.71 



Iron and alumina 11.15 



Moisture .66 



Another sample from near the top of the 7 feet of waterlime 

 gave the following result. 



Silica and insoluble matter 9.92 



Carbonate of lime 68.32 



Carbonate of magnesia 18.90 



Feet 



A 5 Tentaculite limestone, dark blue, with 7 feet of 31J=133J 

 massive layers at the base containing numerous 

 specimens of Spirifer vanuxemi Hall and 

 Tentaculite s gyracanthus (Eaton) 

 Hall (?) Modiolopsis (?) dubius Hall, 



5 p i r o r b i s laxus Hall and Stropheo- 

 donta varistriata (Con.) Hall occur less 

 frequently. Typical Tentaculite limestone. 



A 6 Transitional Tentaculite limestone, in which 11=144J 

 there are fairly thick layers separated by shaly 

 ones. The lower layers contain numerous speci- 

 mens of Spirifer vanuxemi Hall, while 

 an occasional specimen of Tentaculite® 

 gyracanthus (Eaton) Hall was seen within 



6 inches of the top. The complete fauna of this 

 -zone is as follows: 



