124 



VERNON C. ALLISON 



"The Pillar of the Constitution," Wyandotte Cave, Indiana,^ 

 classified by circumference alone (a precarious method) , falls into type 

 lo as being the slowest-growing stalagmite consistent with its circum- 

 ference. The age of this stalagmite has been estimated as follows f 



Authority. 



Collet 



Collet 



Collet 



Hovey 



Present estimate 



Rate of Growth 



cm. per year 

 O.OIO 

 0.017 

 0.02s 

 0.025 

 0.030 



Period of Formation 



years 

 91,000 

 54,000 

 37,000 

 37,000 

 30,500 



Otiuge Na,1 



The stalagmite in the Museum of Science and Art, Edinburgh^ 

 (classified again by circumference alone), required 560,000 years 

 for its formation. Sir Alexander Milne measured the increase on 



the stump which accrued from 

 18 19 to 1863 and estimated the 

 age at 600,000 years. 



The Experimental Mine sta- 

 lagmites fall in t3^e 20, and agree 

 fairly well in vertical growth 

 (0.57 cm. against about 0.60 

 actual) and circumference. 

 These stalagmites are undoubt- 

 edly calcite (W. M. Myers, 

 petrographer, Pittsburgh Station, 

 United States Bureau of Mines, 

 reports that fragments of the 

 stalagmites were uniaxial nega- 

 tive, refractive index from 1.486 

 to 1.658, and gave Meighen's 

 reaction for calcite). 



The change in shape, con- 

 vexity of face, and circumference 

 of the stalagmite from Robertson's Cave, near Springfield, Missouri,'* 

 were probably caused by a sudden increase in drip and an increase 



' Farrington, loc. cit. ^ Ibid. ' Ibid., p. 255. 



4 Farrington, op. cit., p. i; vertical section, Plate 32. 



Gauge No. 3 



Fig. i6. — Jockey Cap stalagmite, 

 Ingleborough Cave, drawn from Daw- 

 kin's measurements, 1873. 



