Locality
Arctic Slope of Alaska locality USGS 11606, north of Maybe Creek. This locality is a bluff approximately 10 m high on the east side of an unnamed tributary of the Price River. The predominant lithologies are bentonitic clays overlying a silty sandstone capped by coal beds up to 2 m thick, which are in turn overlain by a white-gray medium-grained sandstone. Irregularly dispersed throughout the clay are nodules and sheets of ferruginous limestone (sideritic) which, although light gray when fresh, weather to a rusty brown. With the exception of some poorly preserved plant matter in the upper sandstones, and impressions of platanoid leaves in the power sandtsones, the plant material is confined to these fine-grained iron-rich nodules and is preserved as impressions totally lacking cuticle. There is little evidence of post-mortem decay but many leaves are penetrated by vertical fossil rootlets. Platanoid leaves are most common in siltier/sandier facies. The uppermost coal surface supports several in situ tree bases each of which is approximately 20 cm in diameter.
Latitude: 69.528329 °N
Longitude: -153.887128 °W
Description
Leaf: simple; symmetrical; very wide ovate; apex obtuse; base lobate; margin shallowly crenate; teeth with obtuse rounded glandular apices and wide, very shallow, rounded sinuses; venation imperfect marginal basal actinodromous; primary midvein moderate, more or less straight in the basal two-thirds of the lamina, becoming sinuous near the apex; pectinal veins arising at an angle of 80-90°, initially straight or slightly recurved becoming curved with some sinuosity near the margin, meeting the margin approximately one-quarter of the distance between the base and apex, branched, sometimes dichotomously and giving off abmedial veins at varying angles usually approximately 60°, these pectinal abmedials curve abruptly near margin looping to join superadjacent abmedial often at acute angles; superior secondary veins depart midvein at approximately 60°, curved uniformly or with some sinuosity towards the apex, often branched once, sometimes more; tertiary veins percurrent, often simple but frequently branched up to three times, straight to convex when simple, often sinuous when branched; fourth order veins orthogonal to the tertiaries then random reticulate.
Remarks
Actinodromy in this specimen is very poorly developed; the pectinals are markedly weaker than the midvein, do not arise precisely opposite one another, have irregular courses and the area of the lamina served by them and their abmedials is less than one-quarter of the whole. The teeth appear to be intermediate between Platanoid and Chloranthoid although details of the tooth venation are not clear. This leaf is relatively poorly organized by comparison with specimens USGS 11606.67 (form HAPLTL120) and USGS 11480.3 (form DIPE168).