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MUSEUM BULLETIN NO. 2. 
Unconformity at the Base of the Burton. 
Although no structural features emphasize the presence of an 
unconformity at the base of the Burton, yet from other evidence 
such an unconformity is believed to exist. 
(1) . In harmony with the other sections throughout the Rocky 
Mountain geosynclinal, a marine Cambrian transgression is 
represented in the deposition of the Burton formation. 
(2) . The conglomerate at the base of the Burton is composed 
chiefly of hematite pebbles with minor quantities of pebbles of 
quartzite and quartz in a hematitic quartz cement. The 
hematite pebbles, although some have a concentric structure, 
probably represent the results of erosion and subsequent con- 
centration of hematite layers which occur abundantly in the 
underlying Pre-Cambrian series. The quartzite (metamorphosed 
sandstone) pebbles are identical with the quartzite of the un- 
derlying Phillips formation. The occurrence of these pebbles 
already metamorphosed before the deposition of the Burton, 
indicates that a time interval existed between the deposition 
of the Roosville and Burton formations. 
( 3 ) . The grit which overlies the conglomerate is characterized 
by an abundance of milky white quartz particles evidently 
derived from the erosion of quartz veins such as are known to 
be present in the underlying Roosville formation and other 
members of the Pre-Cambrian series. Green particles of the 
Roosville siliceous metargillites are also present and their presence 
supports the idea that the Roosville formation was metamor- 
phosed before the Burton was laid down, hence the idea of a 
time interval between the deposition of the Roosville and 
Burton formations is strengthened. 
(4) . The difference in degree of metamorphism of the Roosville 
and the Burton is very striking in the field. The laminae 
of the Roosville siliceous metargillites are so thoroughly cemented 
together that the rocks always form steep cliffs, in fact the 
perpendicular walls of the Elk River canyon are carved in the 
Roosville formation. In contrast to this the Burton formation 
weathers to a soft earth and is characterized by gentle slopes. 
