A famous outcrop of the Haymond is seen below from Earl F. McBride, "Sedimentary Petrology and History of the Haymond Formation (Pennsylvanian), Marathon Basin, Texas,"  Bureau of Economic Geology, Report on Investigations 57,  1966, Plate 3a. It shows the highly laminated nature of the flysch facies and the clean separation of the sands and the shales.

The sands are described by McBride:

“Quartz is the most abundant framework constituent in all sandstones; it ranges from 57 to 80 percent and averages 67 percent.” Earle F. McBride, “Sedimentary Petrology and History of the Haymond Formation (Pennsylvanian), Marathon Basin, Texas,” Bureau of Economic Geology, The University of Texas, Report of Investigations—57, (March 1966), p.31

Young-earth creationists must be able to explain why the sediment changed from 67% pure sand to nearly pure shale 15,000 times during the flood year. (This deposit could only represent about a month’s worth of time in the flood. There are 15,000 feet of strata in this area.)

The evidence supports the idea that these rocks were deposited in deepwater:

     “The interpretation that the Haymond Flysch sediments accumulated in deep water is based on (a) the presence of quiet-water muds (shales), (b) the lack of textures or structures that form only in shallow-water environments, such as large-scale cross-beds, mud cracks, wave ripple marks, etc., and (c) the absence of shallow-water fossils in the shales—land plant fragments can float, and mud-burrowing animals have been found in modern oceans at abyssal depths. The latter two lines of reasoning imply negative evidence, but they are important aspects where no reliable faunal depth indicators are present.” Earle F. McBride, “Sedimentary Petrology and History of the Haymond Formation (Pennsylvanian), Marathon Basin, Texas,” Bureau of Economic Geology, The University of Texas, Report of Investigations—57, (March 1966), p. 45 

"Tool-mark casts (chiefly groove casts), flute casts and flute-lineation casts are common current-formed sole marks. Trace fossils in the form of sand-filled burrows are present on every sandstone sole, but nearly absent within sandstone beds." Earle F. McBride, "Stratigraphy and Sedimentology of the Haymond Formation," in Earle F. McBride, Stratigraphy, Sedimentary Structures and Origin of Flysch and Pre-Flysch Rocks, Marathon Basin, Texas (Dallas: Dallas Geological Society, 1969), p. 87-88

These burrows are seen in McBride's 1966 Bureau of Economic Geology, Report on Investigations 57, Plate 13A. It is modified from that publication below:

The burrow on the right shows a line of sand particles filling the burrow (the dog-legged line of white.. The burrow on the left is mostly shale filled. The diagonal lines are the saw marks.

But there are other types of burrows in the Haymond. These are horizontal burrows seen below:

Several items can be deduced from these observations.

1. It is obvious that the burrowers prefer to burrow into the shale rather the sand.

2. The burrows in the shale were present when the sand was deposited. Why? because the sand filled the hole (burrow).

3. There were few burrows in the sand as there are no fingers of shale poking down into the sand as there are sand fingers poking down into the shale.

Lets try to explain this in a one year flood. Give each shale layer 1 day for recolonization of burrowers the deposit would require 41 years to be deposited. But that is a real problem. The Haymond bed is 1300 m thick and only represents a small part of the entire geologic column. All the fossiliferous sediments in this area are 5000 m in thickness. To do the entire column in one year requires 1300/5000*365=95 days for the time over which the Haymond must be deposited. This means that 157 sand/shale couplets per day must be deposited. That means that the burrowers must repopulate the shale 157 times per day, dig holes, be buried, then survive the burial to dig again another 156 times that day. Shoot, Sisyphus only had to roll the boulder uphill once a day. What on earth did these burrowers do to deserve this young-earth fate?

We know that the burrowers who were buried did not survive. If they had, they would have had to dig up through the sand to escape their entombment. There are no burrows going up through the sand. And if there had been these burrows, there should be little circular piles of sand with a central crater pocking the entire upper surface of the sand. We don't see these. If they escaped, it should look like:

shale    ^    ^ where the ^ is the dirt thrown out of the burrow when the animal escapes.
----------     ---------------
sand      |   |
----------     --------------------------
shale     | s  |
          | a |
          | n |
          | d |
          ----


As it is, we see this, which indicates no escape of the burrowers. there is no mound at the lip of a burrow at the shale/sand interface:
shale
-----------------------------
sand
---------     --------------------------
shale    | s |
         | a |
         | n |
         | d | 
          ----

And as seen above, there are horizontal burrows which certainly are not escape structures.

This is an indication of lots of time between the deposition of the sand and the digging of the burrows. It simply isn't credible to have these burrowers dig burrows at a rate required by the Noah's flood viewpoint.

As we go east from the Marathon Mountains, these beds go deeper and deeper and are buried by Tertiary sediments which eventually reach 75,000 feet thickness in the region of the mouth of the Mississippi. Because the Haymond is buried by the Tertiary, we know that the Tertiary sediments of the Gulf are younger than the Haymond. Thus if the Tertiary sediment and the Haymond are flood deposits, then the Haymond may only have had less than a month for all that burrowing.

The Haymond also has some boulder beds which have yielded up some limestone conglomerates which are interesting: Palmer et al wrote:

     “In 1982, DeMis noted rare limestone boulders in a previously unmapped conglomerate unit within the Haymond Formation. This unit forms part of a 6.5-km-long dip slope in the stratigraphically highest part of the Haymond Formation exposed beneath the Hell’s Half Acre thrust fault. The unit is composed largely of chert pebbles in a sand-shale matrix, but scattered through the unit in several different graded beds are rare boulders of chert and limestone 10-60 cm in diameter.

“Because limestone boulders are so unusual in the largely siliciclastic Haymond Formation, DeMis collected three small limestone boulders. One boulder yielded several genera of Middle Cambrian phosphatic brachiopods and many trilobites. Nearly all of the trilobite and brachiopod taxa in that boulder were previously described from the Marjum Formation in western Utah and represent the late Middle Cambrian Bolaspidella Zone. The other  two boulders also yielded trilobites and phosphatic brachiopods of the Bolaspidella Zone. Seven more boulders were collected during a short visit to the 0.5 km² discovery area in January 1983.” Alison R. Palmer, et al, “Geological Implications of Middle Cambrian Boulders from the Haymond Formation (Pennsylvanian) in the Marathon Basin, West Texas,” Geology, 12(1984):91-94, p. 91

These trilobites did not come from Utah because the Haymond formation was deposited from the southeast. We know that these limestone rocks were not originally deposited in the Haymond because the Haymond doesn't have any limestone except for these cobbles which were rounded having been washed into place. Indeed large quantities of sand and shale inhibit the growth of limestone depositing organisms.  One can see beautiful limestone beaches around Florida and the Bahamas but none anywhere near the Mississippi River which puts out so much muck that most limestone depositing organisms can't survive the muddly waters.

The sequence of events seen above is as follows::

Trilobites die

Trilobites buried and cemented into a limestone southeast of the Haymond

Limestone rocks are later eroded

Cobbles move down river

Eventually deposited in the Haymond formation

 However, the trilobites were already fossilized when they were ripped up and re deposited in the Haymond formation.  Below are pictures of these already fossilized trilobites in the Pennsylvanian.

Notice that these trilobites show signs of wear and decay prior to their entombment. That means that there was some time span between their death and their dismemberment prior to burial.

I await the young-earth explanation for this data.