368 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 11)02. [mux. 213 
The nature and associations of this marble are subject to great 
variations. An instance of this is the disappearance of red marble 
northeast of Thorn Hill in the belt running north of Clinch Mountain, 
its place being taken by blue and gray marbles. These latter beds 
are of good body, but lack the most prized color. More marked! 
changes are seen in the disappearance of the massive marble and the 
increase of shale in the same belt after it passes southwest from Lut- 
trell. Similar changes are seen east and south of McMillan and 
Strawberry Plains. The position of the marble in the Chickamauga 
limestone also varies. Near the northeast end of Black Oak Ridge, 
and also northeast from Luttrell, the Chickamauga limestone appears 
only above the marble. Along Holston River, however, the limestone 
appears only below the marble, above the latter being the Tellico 
sandstone. In other places the marble occupies an intermediate posi- 
tion. In the next basin north of the Clinch syneline no marble 
appears except northeast of Maynardville, where some unimportant 
beds of gray marble occur. North and west of this no marble has 
been observed, nor does any of consequence occur along the southern 
border of the Maynardville quadrangle. 
The marble above the Tellico sandstone in the base of the Sevier 
shale is comparatively thin and shaly. Occasionally, however, a 
local thickening takes place and the beds resemble the Holston marble 
in all respects. This is notably the case in the area of Sevier shale 
extending southwest from Strawberry Plains past Knoxville. The 
Sevier marble beds are much more variable than those of the Chicka- 
mauga, and there is a smaller amount of workable material in them; ! 
consequently they have not been successfully quarried. 
Other variations in the marble are shown in the disappearance of 
good marble for a few miles in the belt running through the northern 
portion of Knoxville. The belt which is productive south of Knox- 
ville becomes of minor importance 8 miles northeast of Knoxville; and 
the bed at the bottom of the Sevier shale is the productive one in that 
locality. These latter marbles in the region of Knoxville are usually 
shaly and of less value, although they contain many beds of good body 
and color. Workable beds are rarely over 10 feet thick, and usually 
there are several varieties in close proximity. 
Southwest of Knoxville the Holston marble varies in similar fashion. 
It disappears in the belt northwest of Madisonville and shifts down- 
ward into the beds next to the Knox dolomite at Marble Bluff, west 
of Loudon. As a rule, however, the marble in this region remains 
very constantly in the upper part of the Chickamauga limestone. 
The different belts continue south westward to the vicinity of Sweet- 
water. They then disappear rather abruptly and are not found in 
areas farther southwest. 
The marbles of the Sevier shale are prominent at the bottom of that 
formation, but occasionally occur in the upper strata as well. They 
