Ferron Stratigraphy Descriptions Part 2

The type area of (Kf-2-Iv-c) is the mouth of Ivie Creek Canyon. This unit undoubtedly warrants designation as a parasequence inasmuch as the associated transgressive surface is clearly recognizable both in Ivie Creek Canyon and to the south in the I-70 roadcut. The pinch-out of (Kf-2-Iv-c) trends just slightly west of north. The shoreline sandstone unit displays some interesting and unusual changes at the mouth of Ivie Creek Canyon, changing over about 100 yards from a strongly wave-modified shoreface unit to a much lower wave energy unit that contains mud interbeds and finer sand, and that has a silvery-gray color on outcrop. This change suggests a change from a coast directly facing the sea to one that was sheltered from wave energy. In some respects, this resembles the change from (Kf-1-IC-c) to (Kf-1-IC-d). The relationships between (Kf-2-Iv-c) and (Kf-2-Mi-a,b) are presently unknown. It can be speculated, however, that (Kf-1-Mi-a) represents the western margin of a major delta that provided the sheltering from wave energy (see below). Suggested type section: Ivie Creek Canyon, NW1/4SE1/4 section 17, T. 23 S., R. 6 E., Salt Lake Base Line. Seaward limit: not determined. Facies content of shoreline unit: wave-modified coast, probably shoreface in the proximal part, transforming to low-wave-energy coast, possibly ay shoreline.

The type area of Kf-2-Miller Canyon-a is the mouth of Miller Canyon. The boundary between this unit and overlying Kf-2-Mi-b is difficult to recognize in many places, but is very apparent where rotated slump blocks, which are generally restricted to (Kf-2-Mi-a) in this area, are present. The transgressive surface is perfectly apparent where it has bevelled the tops of the rotated blocks, which are common enough to facilitate tracing the contact throughout the “Tri-Canyon” area. The landward limit of (Kf-2-Mi-a) has not been determined. Its seaward feather-edge can be approximately located in Miller Canyon and in the lower part of Muddy Creek Canyon, near the “Upper Gooseneck.” It has a general northeast trend, suggesting that this parasequence built northwestward, probably as a deltaic lobe. The deltaic complex from which this lobe built may have provided the sheltering from wave energy noted for (Kf-2-Iv-c). Rotated blocks are present in (Kf-2-Mi-a) in the Coal Cliffs south of Miller Canyon, in the lower part of Muddy Creek Canyon, and are particularly well exposed in “Grassy Canyon.” A few are present on the east side of “Dino Head Point” on the western margin of the “Molen Amphitheatre.” Failure of the rotated blocks is consistently toward the northwest, the direction that the delta lobe appears to have prograded. The abundance of rotated blocks, which are relatively rare entities elsewhere in the Ferron, in the particular area may once again be related to a zone of flexure. Tilting toward the west may have encouraged failure of the delta-front. Type section: near mouth of Miller Canyon, south side, NE1/4NE1/4 section 36, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: not determined. Seaward limit: Miller Canyon, NE1/4SW1/4 section 26, T. 22 S., R. 6 E., Salt Lake Base Line; Muddy Creek Canyon, CNW1/4 section 24, T. 22 S., R. 6 E., Salt Lake Base Line. Facies content of shoreline unit: river-dominated delta.

Kf-2-Mi-b includes the shoreline sandstone that forms the massive cliffs in the lower parts of Miller and Muddy Creek Canyons. It appears to be a very strongly wave-modified unit. The landward pinch-out of (Kf-2-Mi-b) has not yet been located. It thins toward the northwest into “Grassy Canyon” and the “Molen Amphitheatre”, finally disappearing into marine shale in the southern part of Molen Reef along with overlying (Kf-2-MC-a). In Muddy Creek Canyon (but not yet elsewhere), it is possible to subdivide (Kf-2-Mi-b) into two subunits bounded by a distinctive surface. The southern subunit is wave modified, the northern one very strongly wave modified. The surface that separates these subunits could be a transgressive surface, but the overlying transgressive surface beneath (Kf-2-MC-a) has removed any direct evidence. In the absence of compelling evidence to the contrary, it is assumed the surface marks some change of autocyclic origin. Type section: same as (Kf-2-Mi-a), near the mouth of Miller Canyon, south side, NE1/4NE1/4 section 36, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: not determined. Seaward limit: Molen Reef, CSE1/4 section 29, T. 22 S., R. 7 E., Salt Lake Base Line. Facies content of shoreline unit: wave-modified, probably strand plain in proximal part; may include deltaic deposits in medial and distal parts.

Kf-2-Muddy Canyon-a forms ledges and lesser cliffs above the grander cliffs formed by (Kf-2-Mi-b) throughout most of the lower part of Muddy Creek Canyon and into the southern Coal Cliffs to the south. Most of the thickness of (Kf-2-MC-a) has been cut out by meanderbelt deposits. Although very sandy in some areas, much of the meanderbelt deposit consists of “inclined heterolithics.” Two distinct meanderbelt units are distinguished on the basis of paleocurrent directions, the southern one being the younger of the two. At one locality on the west side of Muddy Creek Canyon north of the “Lower Gooseneck”, the fluvial erosional surface rises to reveal a river-dominated delta-front sequence. On the east side of “Dino Head”, near the southern mouth of “Pinion Jay Valley”, the meanderbelt deposit ends and the delta-front unit, only about 20 feet in thickness, appears. It grades from marine mudstone at the base to predominantly sandstone in the upper part and can be traced continuously through the “Molen Amphitheatre” to a point where it disappears into marine shale in the southern part of Molen Reef. Although a landward pinch-out of (Kf-2-MC-a) cannot be located because of the fluvial erosion, there can be no question that the surface that separates (Kf-2-MC-a) from the underlying (Kf-2-Mi-b) is a transgressive surface: it places offshore marine shale directly upon upper shoreface sandstone and, locally, has planed off small channels within the top of (Kf-2-Mi-b). Type section: southern part of Muddy Creek Canyon, NW1/4SW1/4 section 24, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: cannot be determined owing to erosion by fluvial facies. Facies content of shoreline unit: river-dominated delta; probably represents a low-wave-energy delta that prograded into a protected bay.

Kf-2-Muddy Canyon-b is defined on the basis of a shoreline sandstone unit that has a distinctive white color. The landward pinch-out of (Kf-2-MC-b) is present in the southern Coal Cliffs just north of “Bear Gulch”, at the mouth of Miller Canyon, and is almost reached in the bend opposite the “Lower Gooseneck” in Muddy Creek Canyon. Near the pinch-out, the unit is characterized by large-scale, inclined surfaces that dip to the north, essentially parallel to the trend of the pinch-out (strike of inclined surfaces perpendicular to shoreline trend). The surfaces are interpreted to represent a series of tidal inlets that were driven northward by longshore drift. Equivalent flood tidal delta and lagoonal deposits have been tentatively identified in Miller Canyon and “Bear Gulch.” (Kf-2-MC-b) thickens rapidly eastward, attaining thicknesses in excess of 75 feet in “Grassy Canyon.” It extends eastward into Molen Reef, where it is a major cliff former, and northward to Dry Wash. Its seaward limit has not been precisely identified. The areal distribution of this unit is very large compared to most Ferron parasequences, and it is possible that it can be divided. Type section: southern part of Muddy Creek Canyon, NW1/4SW1/4 section 24, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: southern Coal Cliffs north of “Bear Gulch”, CSE1/4 section 35, T. 22 S., R. 6 E, Salt Lake Base Line; mouth of Miller Canyon, NE1/4NE1/4 section 35, T. 22 S., R. 6 E. and SE1/4SE1/4 section 26, T. 22 S., R. 6 E., Salt Lake Base Line; Muddy Creek Canyon, SW1/4SE1/4 section 23, T. 22 S., R. 6 E., Salt Lake Base Line. Seaward limit: near Dry Wash, approximately NE1/4SW1/4 section 2, T. 22 S., R. 7 E., Salt Lake Base Line, if (Kf-2-MR) is determined to constitute a parasequence (see below). Facies content of shoreline unit: wave-modified coast in proximal part, probably strand plain; may include deltaic deposits in distal part.

The Kf-2 cliffs in the Molen Reef outcrops south of Dry Wash include two distinct upward-coarsening units. They appear to constitute distinct parasequences, the lower being (Kf-2-MC-b), and the upper (Kf-2-MR), but no clear evidence has yet been found to demonstrate that the boundary between them is a transgressive surface. The name is listed here in anticipation that it will be assigned parasequence status. Type section: Molen Reef south of Dry Wash, NW1/4 section 11, T. 22 S., R. 7 E., Salt Lake Base Line. Landward limit: not determined, but approximately NE1/4 section 15, T. 22 S., R. 7 E.,, Salt Lake Base Line. Seaward limit: not determined; somewhere north of Dry Wash. Facies content of shoreline unit: probably deltaic.

Kf-2-Dry Wash is defined on the basis of a shoreline sandstone unit whose landward pinch-out crosses the northern edge of the cliffs of the Molen Reef south of Dry Wash and intercepts the cliffs on the north side of the wash, defining a northwest shoreline trend. The pinch-out is less distinct than most others, possibly because of development of a flood tidal delta in this area. A large lagoon/bay complex lies landward of the pinch-out and can be traced for several miles southward in the Molen Reef outcrops and westward to the limit of Kf-2 outcrops in Dry Wash. The lagoon/bay unit is bracketed by splits of the lower C coal that under- and overlie it. The seaward limit of (Kf-2-DW) has not been determined. It is, at present, the youngest known parasequence of Kf-2. Numerous channel deposits, including three large, lenticular channel bodies in Dry Wash and several in the Molen Reef cliffs appear to belong to (Kf-2-DW). Type section: cliffs north of Dry Wash, SW1/4 section 35, T. 21 S., R. 7 E., Salt Lake Base Line. Landward limit: Dry Wash, SW1/4 section 2, T. 22 S., R. 7 E. and SW1/4SW1/4 section 35, T. 21 S., R. 7 E., Salt Lake Base Line. Seaward limit: not determined. Facies content of shoreline unit: wave-modified, probably strand plain in proximal part; distal part not yet studied.

Shoreline sandstones of Kf-3 extend from the “Molen Amphitheatre” northward beyond Dry Wash. At present, only two parasequences are distinguished. It is likely that one or more additional parasequences will eventually be defined in the northern part of the area of distribution of Kf-3. Much of the thickness of the C-coal bed, previously considered as belonging to Kf-3, has now been reassigned to Kf-2. The uppermost approximately one foot of coal of the C-coal zone, including the thick tonstein bed, extends over the top of (Kf-3-MR-a) near the mouth of “Gnat Canyon” in the “Molen Amphitheatre.” Details of coal correlations farther north have not been worked out. With reassignment of most of the coal of the C-coal zone to Kf-2, Kf-3 becomes one of the leanest parasequence sets in the Ferron with respect to its coal content.

The type area for (Kf-3-Mr-a) is the large “Molen Amphitheatre.” The landward pinch-out of (Kf-3-Mr-a) is very well exposed on the cliffs just to the west of the mouth of “Gnat Canyon.” The pinch-out takes place into the C-coal zone, with about 1 foot of coal passing above, and the remaining 6 to 7 feet passing below. Only 100 feet to the south, there is no trace of the unit within the C-coal zone, which carries its full compliment of tonsteins. This is a remarkable situation. In the majority of cases, transgression of the sea across the Ferron coastal/delta plain led to formation of bays or lagoons that are preserved landward of the pinch-outs of the subsequently deposited shoreline sandstones. In the case of (Kf-3-Mr-a), the transgressing shoreface cut into and partially eroded a mass of peat. The top of the peat must have lay far enough above sea level to preclude inundation southwest of the shoreline. Peat accumulation was only briefly interrupted, if at all, before progradation of the shoreline occurred. Several well-exposed, lenticular channel deposits filled with “inclined heterolithics” complicate the stratigraphy of (Kf-3-MR-a) in the vicinity of its landward pinch-out. Type section: at mouth of “Gnat Canyon” NE1/4SW1/4 section 30, T. 22 S., R. 7 E., Salt Lake Base Line. Landward limit: just W of mouth of “Gnat Canyon”: CSW1/4 section 30, T. 22 S., R. 7 E., Salt Lake Base Line. Seaward limit: not determined. Facies content of shoreline unit: wave-modified, probably strand plain in proximal part; distal part may include deltaics.

Kf-3-Molen Reef-b lies above (Kf-3-MR-a) in the “Molen Amphitheatre”, being separated from it by a thin zone of carbonaceous mudstone. The landward pinch-out of (Kf-3-MR-b) occurs on the floor of “Gnat Canyon” and so is not exposed, although its position can be determined to within one to two hundred feet. As is true for (Kf-3-MR-a), channels are numerous in the landward part of (Kf-3-MR-b). (Kf-3-MR-a) and (Kf-3-MR-b) merge to form the Kf-3 cliff along the Molen Reef, but the parasequences have not yet been distinguished there. Thus, the seaward extent of these two parasequences are not known. (Kf-3-MR-b) is strongly wave modified in its landward part. Suggested type section: east side of “Gnat Canyon” where it merges into the cliffs of the “Molen Amphitheatre.” Type section: “Molen Amphitheatre”, east of “Gnat Canyon”, NE1/4 section 31, T. 22 S., R. 7 E., Salt Lake Base Line. Landward limit: at mouth of “Gnat Canyon”, NE1/4SW1/4 section 30, T. 22 S., R. 7 E., Salt Lake Base Line. Seaward limit: not determined. Facies content of shoreline unit: wave-modified coastline, probably stand plain, in proximal part; distal part may include deltaics.

Compared to the parasequence sets that preceded it, Kf-4 thickens very rapidly seaward, indicating a high rate of relative sea level rise during its deposition. Two parasequences are recognizable, although a third may prove to be distinguishable in the “Fracture Canyon” area. The associated G-coal zone only locally contains more than a few feet of coal, probably because peat accumulation could not keep up with the rapid relative rise of sea level that characterized this unit. Carbonaceous mudstones of the G-zone have been mined to produce a soil conditioner, locally referred to by the trade name “Live Earth”, for about 20 years in Miller Canyon, although that mine appears to now be inactive.

The type area of (Kf-4-Mi) is the mouth of Miller Canyon, where its shoreline sandstone body forms high cliffs. The landward pinch-out of (Kf-4-Mi) occurs just south of “Bear Gulch”, but is somewhat obscured because the upper part of the unit is replaced by a meanderbelt deposit. The meanderbelt deposit is very widespread, being recognized throughout the “Tri-Canyon” area and eastward into the “Molen Amphitheatre.” It is also relatively coarse-grained, being made up of medium- to coarse-grained sandstone that locally includes granules and, rarely, pebbles. The landwardmost part of (Kf-4-Mi) is strongly wave modified and this is probably true of the unit as a whole, although it is difficult to tell with the upper part of the unit removed. Type section: southern Coal Cliffs at the mouth of Miller Canyon, SE1/4SE1/4 section 26, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: in Coal Cliffs south of “Bear Gulch”, SW1/4NE1/4 section 2, T. 23 S., R. 6 E., Salt Lake Base Line. Seaward limit: not determined, probably in southern part of Molen Reef. Basic facies content: wave-modified shoreline–strand plain in proximal part to wave-modified delta in distal part.

(Kf-4-MR) is defined on the basis of a shoreline sandstone unit that forms a striking, white wall throughout the “Molen Amphitheatre” area. The landward pinch-out of (Kf-4-MR) is well exposed just west of the mouth of ” Gnat Canyon”, almost directly above the landward pinch-out of (Kf-3-MR-a). Pronounced landward thinning toward the pinch-out is also evident in “Pinion Jay Valley” and in the area north of “Molen Point.” (Kf-4-MR) is extremely wave modified in its landward part. The more distal part, however, may include some lower-wave-energy shoreline deposits, some of which may represent river-dominated deltas. It may be that the latter constitute one or more additional, as yet undefined parasequences. Type section: Molen Reef, SE1/4SW1/4 section 29, T. 22 S., R. 7 E. or along white, south-facing wall in “Molen Amphitheater”, SE1/4SE1/4 section 30, T. 22 S., R. 7 E., Salt Lake Base Line. Landward limit: mouth of “Gnat Canyon”, NE1/4SW1/4 section 30, T. 22 S., R. 7 E., Salt Lake Base Line. Seaward limit: not determined. Probably extends most of the way up Molen Reef toward Dry Wash, where a younger parasequence may be present. Basic facies content: wave-modified shoreline–strand plain in proximal part to wave-modified delta in distal part.

Kf-5 thickens rapidly seaward from its landward limit in Muddy Creek Canyon. Its seaward feather edge lies in “Fracture Canyon” just south of Dry Wash. Kf-5 has, to date, defied division into parasequences. Almost everywhere, the upper part of the shoreline sandstone of Kf-5 has been cut out and replaced by meanderbelt deposits (among them the channel deposits so extensively studied by the Texas Bureau of Economic Geology in Muddy Creek Canyon, Grassy Valley, and “Cedar Canyon”). The presence of the meanderbelt deposits preclude recognition of the landward pinch-outs of any parasequences that Kf-5 contains. Most of the shoreline strata of Kf-5 appear to represent a wave-modified coast, probably a wave-modified delta front. The I-coal zone accumulated in a swamp, probably a “raised mire” that existed along the western margin of the Kf-5 meanderbelt that trends northward to northeastward across Muddy Creek Canyon. Coal in the I-zone reaches its maximum thickness in the area at and south of Christiansen Wash, where it combines with the overlying J-coal to form a 30-foot-thick seam. Although the A- and C-coal zones probably include more coal because of their greater areal distributions, the I-coal bed is the only one that has been mined on a large scale. The lower 20 feet of coal has been extensively mined by conventional, room-and-pillar techniques at the Emery mine. The upper 10 feet of coal, which tends to be higher in sulfur, has been left as roof. Consol estimates that about 100 million tons of combined I-J coal is strippable in the area south of Emery. Carbonaceous mudstones of the I-zone are being mined as “Live Earth” south of “Bear Gulch”. Type section: none. Considered to be a parasequence set at present. If Kf-5 is ultimately considered to constitute a single parasequence, a good type section would be the west side of Muddy Creek Canyon, NE1/4SW1/4 section 13, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: Muddy Creek Canyon, somewhat obscured because of overlying meanderbelt, approximately NW1/4 section 24, T. 22 S., R. 6 E., Salt Lake Base Line. Seaward limit: “Fracture Canyon”, SW1/4 section 24, T. 21 S., R. 7 E., Salt Lake Base Line. Facies content of shoreline unit: river-dominated delta.

Kf-6 extends from the upper part of Muddy Creek Canyon to Dry Wash. No parasequences are recognized at this time and it is likely that none will be. Contemporaneous channels are rare or absent and all of the shoreline strata of Kf-6 appear to have accumulated along a wave-dominated coast, probably a strand plain. Kf-6 is difficult to study in detail owing to the fact that it is generally exposed only on the lower part of the Molen dip slope and because outcrops are generally poor between the few significant canyons. Both the landward pinch-out at the head of Muddy Creek Canyon and the seaward feather edge at Dry Wash, however, are particularly well displayed. Type section: uppermost part of Muddy Creek Canyon, SE1/4NW1/4 section 13, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: uppermost part of Muddy Creek Canyon, SE1/4NW1/4 section 13, T. 22 S., R. 6 E., Salt Lake Base Line. Seaward limit: Dry Wash, NE1/4NW1/4 section 34, T. 21 S., R. 7 E., Salt Lake Base Line. Facies content of shoreline unit: wave-modified coastline, probably strand plain.

The landward limit of Kf-7 lies somewhere in the vicinity of Christiansen Wash, although it cannot be defined for lack of good outcrop and the fact that it has been cut out by a major meanderbelt deposit. It reaches a seaward feather edge in the northern part of Muddy Creek Canyon. No parasequences are presently distinguished and, because of outcrop limitation, it is likely that none will be. All well exposed parts of the shoreline unit of Kf-7 are of lower and middle shoreface strata. Dominance of hummocky-swaley cross stratification and planar lamination coupled with moderate bioturbation point to a wave-modified shoreline. The presence of the thick, multi-storied, contemporaneous meanderbelt deposit at Christiansen Wash demonstrates that a large river was actively feeding sediment to (Kf-7) in the area between Christiansen Wash and Miller Canyon. Type section : west side of Muddy Creek Canyon, NW1/4SW1/4 section 24, T. 22 S., R. 6 E., Salt Lake Base Line. Landward limit: cannot be determined owing to fluvial erosion, approximately at Christiansen Wash, NW1/4 section 33, T. 22 S., R. 6 E., Salt Lake Base Line. Seaward limit: upper part of Muddy Creek Canyon, SE1/4NW1/4 section 13, T. 22 S., R. 6 E., Salt Lake Base Line. Facies content of shoreline unit: wave-modified shoreline, probably strand plain in proximal part and certainly wave-modified delta in distal part.