Sedimentary structure, trace fossil, or leaf print?

[kgbudge]

I don't think I've posted this here before. Any ideas? It's from the Moenkopi Formation near Temple Mountain, San Rafael Reef. Probably Moody Canyon Member, but it's detrital so I can't be 100% sure. Would be Early Triassic.

 

Looks a lot to me like tire tracks, but the geologic age is wrong for that.

[piranha]

 

"The red beds of the Moenkopi are characterized by abundant sedimentary structures that testify to their accumulation on mud flats and deltas. Current ripple marks, exceptionally abundant, cover siltstone surfaces over wide areas. Cross-stratification, particularly of small-scale varieties, is moderately common in the coarser-grained detritals. Casts of salt crystals, rain pits, and other structures of subaerial origin are locally numerous, and the footprints of vertebrate animals are common at many horizons."

 

"Less numerous varieties are those resulting from combinations of the fundamental types, referred to as "imbricated or complex" by Kindle (1917, p. 29) and as cross-ripple by Twenhofel (1939, p. 526). An example in which a set of symmetrical ripple marks was later altered by current ripples moving at right angles to form rows of irregular knobs has been collected. Another in which current ripple marks have had their troughs partitioned off into squares by the crests of wave marks, apparently after water had receded to a very shallow depth, is illustrated in Plate 7A."

 

figure 7A and text from:

 

McKee, E.D. 1954
Stratigraphy and History of the Moenkopi Formation of Triassic Age.

Geological Society of America Memoir, 61:1-133

[kgbudge]

So, sedimentary structure. A pretty nice example of a pseudofossil.

[kgbudge]

For grins, here's some more Moenkopi Formation ripplestone with fairly unusual scour marks.

[Sjfriend]

On 11/11/2021 at 12:57 PM, kgbudge said:

 

Looks a lot to me like tire tracks, but the geologic age is wrong for that.

Finally, proof the Flintstones existed 

 

Love those ripple marks!