Geoscience Reference
In-Depth Information
Fig. 4
Generalized geology of the Red River Valley (modified from Autin and Pearson
1993
)
Louisiana), and at Colfax, Louisiana. The river is also flanked by terraces and
uplands of Pleistocene fluvial deposits. The sediments then mix with the fluvial
deposits of the Mississippi River as they transition to the broad Pleistocene units of
the coastal plain (Autin and Pearson
1993
).
Geomorphic and Historical Development of the Red River Valley
The Holocene valley of the lower Red River was characterized by numerous
rapidly meandering channels. The Raft extended for miles upstream and had a
major influence in the development of this valley, as it affected the intense
meander activity of the river. During the Quaternary, the Red River migrated
several times and moved either independently or by means of an abandoned
Mississippi River channel to the Gulf of Mexico. The Red River also joined the
Mississippi River channel several times in the geologic past with the combined
rivers (Aslan et al.
2005
) flowing into the Gulf of Mexico.
According to a late Holocene reconstruction by Aslan et al. (
2005
), the Mis-
sissippi River avulsed three times in south Louisiana. Around 5,000 year B.P., the
Mississippi River flowed along the western margin of the Mississippi valley
through what is now Bayou Teche or Mississippi Meander Belt 3 (Saucier
1994
),
and joined the Red River to flow to the Gulf of Mexico (Fig.
5
). The Mississippi
River separated from the Red River by 2,000 year B.P., avulsed eastwards to the
south of Vicksburg to form Mississippi Meander Belt 2 (Fig.
6
). No later than
approximately 900 year B.P., the Mississippi River completely shifted to the
eastern side of the valley, forming Meander Belt 1, while the Red River avulsed
northeast and reoccupied an abandoned channel of the Mississippi River Meander
Belt 2. The river then joined the Mississippi River close to where the current
Search WWH ::
Custom Search