June 22, 2010
Rios Tzaconeja and Soledad, Chiapas

(Latest notes from Ron Canter)

RIO TZACONEJA [Tzajalob] – approx. 24 km, in two segments, may be navigable

Though the river is all whitewater in its several canyons, two
sections of the Rio Tzaconeja may have been navigable in the past. The
headwaters were not. They funnel into fault-controlled Encajonado Huistan,
which runs straight east for 30 km to Cerro Chajlib. In the last 10 km
from Naranjal to the Altamirano bridge, Class 3 and 4 rapids are frequent,
with a couple of portages at bad spots (Mayan Whitewater, 2010).


At the bridge, the river enters a large valley, which stretches east
40 km to Bambu, near the Rio Soledad. It is the counterpart of the valley
of the Rio Jatate Superior, to the north just over the ridge of the Sierra
Corralchen. The Tzaconeja valley does not have a known site corresponding
to Tonina, the major Maya ruin in the Jatate’s valley.
For about 9 km from the Altamirano bridge to another bridge at
Pimienta, the Rio Tzaconeja is flat, a short navigable segment. There are
sandbars on bends. At Pimienta the upper valley abruptly ends. 13 km
after exiting one canyon, the river enters another of sorts, where the
elevation of the valley floor steps down 360 m in 7 km. The river is
pinched in a tight, ever-deepening gorge between two parallel ridges. The
gradient of up to 150 m/km (500 ft/mi) indicates waterfalls rather than
rapids, and that is what the river holds (Mayan Whitewater, 2010).
A step where a river crosses a resistant rock layer or a fault scarp
is not surprising, but one midway in a limestone valley is. The falls
appear to be actively receding, The obvious geological explanation would be
that the river once flowed serenely at a higher level before a tributary of
the Rio Jatate breached the eastern ridge and captured the river. The much
lower Jatate would have become the new base level for the Tzaconeja.
Erosion would then progressive lower the valley floor to the new local base
level, leaving remnants of the former valley to either side at the
1100-1200 m level. Modern roads follow these terraces rather than the
valley floor. Where a former high-level outlet might have been is not
clear. Possibly the river joined the Rio Soledad to exit through the dry
gorge at the head of the Rio Dolores. It is also not out of the question
that the water flowed northwest, and then north, to join the upper Jatate
above Tonina.
The Rio Soledad is part of the puzzle. It too has a huge descent,
Salto Grande, where it tumbles 500 meters into the Tzaconeja valley at
Bambu. If the valleys were not so remote, both canyons and falls would be
major attractions.
The Tzaconeja’s next segment is reported to be flatwater for about 24
km. On Google Earth the first 9 km appear to have occasional rapids. Only
the 15 km from Chiptic to the mouth of the Rio Soledad appear to actually
be flatwater (Mayan Whitewater). In the 4 km from the Soledad to the
hammock bridge at Bambu, the Tzaconeja is braided and choked with sediment
from its tributary.
In the lower valley is the Tzajalob site (Blom, 1953), located on the
right shore about 3 km south-southwest of Venustiano Carranza. The John
Geddings Gray Memorial Expedition investigated a cruciform tomb here in
1928 (Blom, 1954). From the description, it was most likely from the
Classic. Whether there were other ruins is unclear. The tomb is at about
the midpoint of the extended valley, and near the start of the lower
navigable section.
The easiest trail exit from the Tzaconeja valley is not at the east
end, where it funnels into a canyon, but rather 10 km earlier at El
Triunfo. A pass in the Sierra Corralchen leads into the valley of the Rio
Colorado at San Marcos, and joins the route from Tonina to the Rio Jatate
at Topiltepec.
Where the valley pinches to an end about 6 km below the Rio Soledad
junction, the Tzaconeja cuts through a mountain for 5 km. The rapids start
right at the bridge in Bambu. With a gradient of 15 m/km, the Tzaconja has
pool-and-drop Class 5 to 5+ rapids in the Lower Canyon (Mayan Whitewater,
2010).
Down the Tzaconeja only a few km more, there is another, shorter
canyon, with waterfalls four km upstream of the Rio Colorado junction (The
Colorado itself is nothing but rapids and falls for 7 km upstream). Just
below the Rio Colorado is the village of Romulo Calzada, with road access.
The last 2 km of the Tzaconeja surges through a final gorge before joining
the Rio Jatate at the Topiltepec site, near Sultana.

RIO SOLEDAD [Indepencia] – Not remotely navigable in the past
A tributary of the Rio Tzaconeja, the Rio Soledad is too small and
steep to have been navigable. It runs southeast, and then turns to the
north around the peak of Montana Chac (2050m). The Soledad begins as a
small river in a broad valley with a floor at 1200 to 1300 meters in
elevation. The little river has sandbars and mild rapids as far as
Indepencia, where it drops over two waterfalls and begins its descent.
The upper valley is a hanging valley, 500 m higher than that of the
Tzaconeja where they join. For 10 km the Soledad tumbles down the Salto
Grande through a red walled canyon (Blom, 1953). The barren canyon walls
are very actively eroding. At the exit a huge, braided outwash fan extends
for 3 km to the Rio Tzaconeja.
East of Indepencia, the wide, nearly flat valley of the upper Soledad
continues at 1200 m, only there is no river in the valley. Southeast 11 km
from Indepencia is the head of a winding gorge leading to the upper Rio
Dolores, a tributary of the Rio Santo Domingo. The 10 km long gorge is now
dry, but was obviously once a stream course. The Soledad formerly drained
south through the gorge, but its waters have been captured and diverted
north to the much lower Rio Tzaconeja.
There is a chain of Maya sites down the Soledad valley: Puerto Rico,
El Amparto, and Santa Elena Poco Uinic. Largest is the Late Classic Santa
Elena Poco Uinic site, perched on a promontory bounded by the canyon (MARI,
1940, Mathews, 2009). It has architectural ties to Chinkultic and Tenam
Puente 40 km father south. To the west of the canyon, a trail descended,
and then sidled along the much larger valley of the Tzaconeja.
The sites and passes suggest that the Soledad valley would have been
something of a crossroads in the Classic, a pathway to any of several
routes southeast to the Rio Santo Domingo. On the east side is a pass to
the upper Rio Euseba valley. At the southeast end of the Soledad valley, a
pass slides past Cerro El Calvario to the Rio Caliente’s valley.

Ron Canter 6-22-10

Posted by Dave at June 22, 2010 05:09 PM