The deposits building the cone accumulate on gyttja
, the ceiling of which was dated to 7496 (95.4%) 7082 cal.
ERI and RCPT measurements conducted during expressway construction have contributed to the recognition of soils of low bearing capacity such as organic soils (peats, gyttja
and aggradate muds).
Nevertheless, Anselmetti et al.'s soil erosion study of Lake Salpeten (directly east of Lake Peten Itza) records a tenfold increase in soil erosion rates starting at 2200 BC (134 t/[km.sup.2] [yr.sup.-1]) over the previous average in the pre-Maya gyttja
(16.3 t/[km.sup.2] [yr.sup.-1]) (: 916).
It was made on a gyttja
bulk sample taken from a borehole which was situated 740 m NW from the Palanga site (Fig.
This dating is also supported by the lithology (not shown here, but see Saulnier-Talbot et al., 2009), including clay at the bottom of the sequence, followed by a transition to a more organic gyttja
. The QUA core covers about half of this period (3800 years), and the TKQ core, only about the last two millennia.
Unlike Butenai and Snaigupele, the lithology of the section is not uniform: the lowermost layer of silt is overlain by gyttja
, the latter is covered by peat and the upper part consists of sand.
The percussion coring of the basin further showed that coarse diamicton is overlain by coarse, granite-rich, moderately sorted sediment which, in turn, is overlain by alternating layers of gyttja
and wetland sediment.
Amazingly, the artifacts have been perfectly preserved because of the abundant oxygen-consuming "gyttja
"-a black, gel-like sediment which is formed when peat begins to decay.
The analyzed sediments sequence consisted of green-grey lake mud (gyttja
deposition initially occurred in the third bog and then was followed by marl deposition.
The sediments in all the studied cores consisted of dark-brown unconsolidated, highly porous, homogeneous gyttja
. Changes in the water content were similar in all four cores (Fig.