Sagwon Section 2

The sedimentary log and environmental interpretations shown on the left was produced by Anders Ahlberg during fieldwork in 2005.

Major coals I and II are laterally continuous throughout the Sagwon section, as well as some minor coal seams. Sample numbers in the figure on the left are predominantly pollen or coal samples. Leaf fossils were found both in situ, as float at the base of the section and in the erosional gully that follows the anticline axis.

Coal I is rooted and probably formed in situ on an upper delta plain before subsidence drowned the peat to form a pond. The lacustrine silts that accumulated in this pond also yield locally abundant remains of the water plant Quereuxia.

Coal II appears not to be rooted but contains numerous fusain (charcoal) layers evidencing repeated wildfires. It is likely, therefore, that despite the lack of rooting the precursor peat formed in situ and was not an allochthonous accumulation of plant debris in a pond catchment.

Most of the leaf fossils found in this area are found in siderite nodules in situ in the stream bed that is close to the axis of the Ivishak anticline, or as loose siderite blocks in the stream bed. Overall the flora is typical of the Early Sagwon phase of floral evolution.