Table 2.

Lithological descriptions and interpretations for the six facies represented at the majority of plant bearing outcrops in the Markley, Harpersville and Archer City formations

	Lithology	Interpretation
Channel sandstone	Lenticular bodies of tan-reddish tan, fine to very coarse sand. Can  be locally conglomeratic. Cross-beds present. Individual beds  often pinch and swell in thickness at outcrop scale. Overall, this  unit is virtually non-fossiliferous, with only a small number of  identifiable plant fossils and unidentifiable stem fragments  observed at a few localities. Sharp, erosional basal contact.	Fluvial channel  deposit
Floodplain  mudstone	Medium grey mud/silt. Weathers to tan-rusty red. Well to fair  bedded, ripple laminated, often fissile. Charcoal fragments  widespread, but sparse. Plant fossils may be abundant  (sometimes covering entire cleaved surfaces of a hand sample) in  some intervals and absent in others, with no observed  lithological differences between fossiliferous and  non-fossiliferous intervals. Basal contact typically indistinct,  with interbedded organic shales gradually thinning and being  replaced by this unit.	Fluvial  floodplain  deposit
Mudstone parting  beds	Medium grey, poorly bedded clay. May contain charcoal fragments.  Beds are thin (<10 cm) and are deposited within organic shale  beds. Plant fossils are usually present, often in abundance.	Fluvial channel  deposit
Organic shale	Chocolate brown, organic-rich, fissile mud/silt. Weathers to rusty  brown. Charcoal fragments (usually < 2 cm in diameter and  <5 mm thick) widespread, sometimes in abundance. Bedding is  very thin and planar. Coal deposits locally present, ranging from  1 cm to nearly 1 m thick. Coal is sub-bituminous and impure.  Thicker coal beds often contain several interbedded shaly,  clastic-rich intervals. Organic beds may be rich in fossil plant  foliage, but may also be dominated by stem fragments, almost to  the exclusion of foliage. Basal contact gradational for c. 2–5 cm  from underlying grey clay to more organic-rich mud.	Swamp deposit
Quartzitic-kaolinitic  siltstone	Light to medium grey, quartzitic silt/fine sand clasts in a  kaolinite-rich matrix. At outcrop scale, bedding is clearly  present; hand samples usually show poorly developed bedding.  Plant fossils locally abundant or absent. Sharp basal contact. At  outcrop scale, this unit is typically lens-shaped, indicating an  erosional base or deposition in a topographic depression.	Fluvial channel  deposit
Basal palaeosol	Grey to reddish grey, mottled claystone, enriched in kaolinite and  iron oxides. Has blocky structure. No bedding present. Colour  differences are present in basal palaeosol outcrops, probably due  to soil horizonation. This unit contains root traces and root casts,  but no identifiable plant material was observed. This unit is  identical to the ‘Type B paleosols’ described by Tabor &  Montañez (2004).	Palaeoultisol