PERMFILE70533

• Permit No: C1981048
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT IV-1 THRU IV-6
• Media Type: D
• Archive: No

14O CONTRIBUTIONS TO ECONOMIC GEOLOGY
has been truncat~ Paleocene erosion,to Amaximum thickness of
310 feet in a well drilled southwest of tees Black Hills. The Trinidad
sandstone is very well exposed along tees eastern margin of the coal
field between Trinidad and Wnlsenburg as a massive cliff or series of
ledges. Elsewhere it is covered or poorly a:posed, but nevertheless
forms a bench above the softer underlying Cretaceous shale beds. _
The Trinidad sandstone consists of one to three light-gray, gray,
and buff slightly arkosic sandstone beds with thin interbeds of light-
gray, gray, and light-tan silty shale. The sandstone is medium thick
to thick bedded, and is most commonly in tabular beds. However,
the bedding may be occasionally irregular and infrequently lenticular.
The sandstone is glJartzose lvitll some weathered feldspar, mica, and
ferromngnesian minerals. The sandstone is predominantly fine
grained but the grains range from very fine to medium size.
Cementing materials are calcium carbonate, cloy, and Silica, and
cementation varies from good to poor. Caste and molds of Halyfne-
nztea sp. are abundant.
VEAlIFJO FOSKdTION
The Vermejo formation (Lee, 1913, p. 531) of 1lfontnna and post-
bfontnnn age rests conformably on the Trinidad sandstone over most
of tees Ilnton 1lfesa region. TIJe base of the formation is drawn rat the
top of the highest sandstone bed in the Trinidad sandstone. The
formation is apparently absent several miles southeast of Trinidad,
but increases irregularly in thickness northwestward to a maximum
of 650 feet southeast of Cuchara Pass. West of Ln Vetn the average
thickness of the Vermejo is about 375 feet, but the thickness varies
from n thin edge where it ie truncated by the erosion surface at the
base of the Poison Canyon formation. The Vermejo formation is
genornlly poorly exposed throughout tees Trinidad coral field, except
along canyon walls, gullies, and road cuts.
The formation consists of complexly interbedded gray to black
carbonaceous, coney, rand silty shale; buff, gray, rand grey-green
lightly arkosic sandstone; buff, gray, rand dark-gray carbonaceous
siltstone; sled ninny coal beds. Most of the thinner sandstone beds
have parallel bedding rand parallel lamination, but the thicker beds
are lenticular rand irregular. Grains in the sandstone beds range from
very fine to medium, rand most are quartz with fee~er grains of
(veathered feldspar, mica, rand ferromngnesinn minerals. The cement-
ing materials are clay rand calcium cnrbon:de. Coal is interbedded
with beds of siltst.one rand shale n few inches to ninny feet thick
(fig. 19). The lower few feet of the Vermejo formnt.ion are usually
made up of shale, siltstone, and coal throughout much of the coal
•
RESOURCES OF TRINIDAD COAL FIELD, COLORAD~ 141
Flvune ]0.-CaYedsle east Led Iv upper pert of YermeJo fnrmetlnn north of Purgn tolre
Illrer. Con6lomerv lln enndnlone al Ln ae of Raton [ormullvn tope LIuR to le[I. Threo-
fou rthe of u mile south o! Cohedale, Colo. Vlerv la eveta~vrd.
field, but locally the basal part is made up of sandstone beds somc-
whnt similar to those of the Trinidad sandstone.
Len (1917, p. G}) believed that the rocks of the Vermejo formation
were partly removed from the western port, of the c•onl Held and en-
tirely removed from the eastern part by widespread post-Crahtceons
erosion. however, no evidence has been found of n regional uncou-
formit.y between the Vermejo fm•nultion and the ocerl}'iu~ Raton
formation. The contact is sharp, rand the southeastward thinning of
the Vermejo seems to be due to uoudeposilion rather than pre-Ilalml
erosion.
MES020IC 6ND CENOZOIC ROC%8
ItOCK6 OF CRETACEOUS AND TERTIARY AOH
RATON FOARdTION
The Raton fm•nuntion (Lac, 1913, p. 531) is of Late Crehlcemis and
Paleocene age (13rowu, 1917, p. 83), rand comprises the surface rocks
over large parts of the Trinidad coal Held. The formation is usual)}'
well exposed along the eastern edge of the coal field between Ibe
:lpishapn and Purlrntoire Rivers, nlmng the Purgnloire River, and
nDODOD 0-01-3