IGNEOUS ACTIVITY IN EAST KENTUCKY 613 



different western localities by Hewett, 9 the bentonite being formed only 

 from the very fine volcanic dust particles where they fall on salt or brack- 

 ish water and are coagulated and settled on the sea-bottom. 



Evidence of igneous Activity in East Kentucky 



Having arrived at an estimate of the volume of ash material ejected by 

 this volcano, it is seen that this must have been one of the large, deep- 

 seated volcanoes of the earth, and to have been in a region where other 

 evidences of volcanic action and of mineralization, such as accompany 

 such action, occurs. Such a volcano may have, from time to time during 

 the succeeding ages, broken forth for short intervals of time either by 

 ejecting other ash material or by sending out dikes of igneous rocks, 

 theoretically such dikes becoming more basic as time passed on and this 

 volcano reached its old age. Basic igneous rock in the form of peridotite 

 dikes do occur in northeastern Kentucky, in Elliott County. 10 Such 

 dikes, which cut up through the Carboniferous rocks, may represent the 

 last extrusions from the neck of this volcano emanating out of this deep- 

 seated igneous mass many ages after the acid ash fall. It is considered 

 by Phalen that these dikes are of early Mesozoic age. 



The presence of these peridotite dikes in northeast Kentucky might be 

 considered as another link in the chain of evidence locating this ancient 

 volcano in this section of Kentucky, and with this added evidence it is 

 felt that this volcano must be buried under the Cumberland Mountains 

 of Elliott or adjoining counties to the south. Additional evidence of vol- 

 canic activity in the mountain section 125 miles to the south of Elliott 

 County is shown in the presence of a, dike of basic igneous material occur- 

 ring in Union County, Tennessee, on the east side of the Cumberland 

 Mountains. This dike, which was found by Watkins 11 about 1912, is 

 about 30 feet wide and is composed at the present time for the most part 

 of chlorite and serpentine with some garnet and magnetite. This is prob- 

 ably another altered peridotite dike. 



Report of E. S. Larsen on Tennessee Bentonite 



Samples of bentonite from Singleton, Tennessee, were submitted to 

 Esper S. Larsen, of the U. S. Geological Survey, for determination. 

 Larsen states that this material is a decomposed rhyolitic ash that has 



9 D. F. Hewett : The origin of bentonite and the geological range of related material 

 in Big Horn Basin, Wyoming. Washington Academy of Science Journal, vol. 7, April 4, 

 1917. pp. 196-198. 



10 W. C. Phalen : Kenova quadrangle. U. S. Geol. Survey. 1912. 



11 Joel H. Watkins : Personal letter, 1921. 



