BATON ROUGE, LOUISIANA 30 x 60 MINUTE GEOLOGIC QUADRANGLE SERIES 91°00' 92°00' 45' 30' 15' 30°30' 30°30' Hb POINTE COUPEE PARISH Hua Pph Hb WEST BA Description of Map Units Hml3l Hal Hmm3l Had IBER H S H S I I Hua Hb R R Pph VILLE P A Hb A Hmc3u Hb Maringouin TON ROUGE P HOLOCENE Hml3u Hb Hb Hal Pph Undifferentiated alluvium of small upland streams—alluvial deposits of minor ARISH Hml1 Hmm3u Hac Hua creeks and streams filling valleys cut into older deposits. The modern flood plain within E G U Hmd1 Hb O Hml3l I B Hua these valleys constitutes the surface of these deposits. The lithology reflects the lithology E P R Hrm ARISH N Hb Hb S R Hmd1 of the older deposits from which they have been eroded and reworked. T V O P E G U O R N O M I T L T A L A BATON ROUGE Backswamp deposits—Holocene deposits of the Mississippi and Atchafayala rivers. Hb R E B Hb A B They consist of fine-grained, usually clayey and often organically rich sediments that TI Pph T Hmm3l N T Had S underlie flood basins between meander-belts. Hml3u Hml3u S Hua B E B P A A Hb a E a W y R y o Small river deposits, undifferentiated—undifferentiated alluvial deposits of small I o u P S Hb Hs A u Port Allen R H rivers consisting of recognizable but unmapped natural levees, distributaries, and T I Hml3u e S M abandoned channels. c H Hb h S a T LANDRY e B Hml3l r Hmm3u a i —sinuous tonal pattern interpreted to be an abandoned river River channel remnants n y P Hcr o g A Hua channel, buried beneath backswamp and natural levee deposits. u o Pph R u A Hmm3l IS i Hmd1 n t P c o Hac H h B ATCHAFALAYA RIVER DEPOSITS r Hb t a Hal a a f y g a o e la u Crevasse complex of the Atchafalaya River—silty, sometimes sandy, deposits of y Hal a YHb U Hac crevasse splays originating from the Atchafalaya River. Hb G A D Ppbce Hmm3l Hb Hb ro Hb RW s TE Hb U s A D e Hua Distributary complex of the Atchafalaya River—silty to sandy, natural levee AL W Had Hb T deposits of distributaries originating from the Atchafalaya River. Had e t e Natural levee deposits of the Atchafalaya River—the silty to sometimes sandy S INTRACOAST Pph T Hal overbank deposits that compose the low natural levees that flank the Atchafalaya River. H Lmc3u S AN Hal Hb T D Hml1 Lacustrine deposits—fine-grained, generally clayey deposits of areas created by the M RY Hb Hmd1 Hmm1 Hala A P Hml1 Hua infilling of lakes by Atchafalaya River distributaries. R A Hac Hal Hb TI RI Hb Hmc3l N SH PA Hua Ppbcl RI Arnaudville Pph LAFOURCHE DELTA LOBE DEPOSITS SH Hmc1 U Hmm3l Had D Hal Hb Lafourche meander-belt—clayey deposits filling the abandoned main Mississippi River Hml3l Hlm channel of the Lafourche delta lobe. Locally, these deposits may include younger natural Hs Hb Pph Hmc3u Hal Hal levee and overbank deposits of the modern Bayou Lafourche that are too small to map at Hml3u this scale. Hml3u Hmc3l Hb Hb Hmm3u Hal Distributary complex of the Lafourche delta lobe—silty to clayey natural levee Hb Hua Hua Hld Ppbcl Hac Hml1 Hmm1 Pph deposits of distributaries originating from the Lafourche meander-belt. Had Hb Hmc3u Hb Natural levee deposits of the Lafourche meander-belt —the silty to sometimes LAF Ppbce Hrm Hmd1 AYETTE Hb Hll sandy deposits that compose the low natural levees that flank the Lafourche meander-belt Hmc3u Hb PARISH Hb Hb and it's main distributary channels. Hac Hb Ppbcl Hb Hb Hb er Hml3l Hua MISSISSIPPI RIVER DEPOSITS iv Hb Hmd1 R Hb Hb Hal Hb Hac Hb Hua Mississippi River meander-belt No. 1—point-bar channel deposits and abandoned Hb Hmm1 channels associated with the modern course of the Mississippi River. Hs p Hml1 m —silty to sandy a Hmd1 Hua Crevasse complex of Mississippi River meander-belt No. 1 Ppbe on Hmm3l Hb Hb li w R Pph Hmc1 deposits of crevasse splays originating from meander-belt No. 1. i ive Hb Hua m S r r Hb e Hmd1 Hml3u Hmm1 Distributary complex of Mississippi River meander-belt No. 1—silty to clayey, V Hal n Hmd1 o W natural levee deposits of distributaries originating from meander-belt No. 1. s Hcr Hb r Hal h WEST BATON ROUGE PARISH Hmc3u e i e s Natural levee complex of Mississippi River meander-belt No. 1—silty to sandy h d k EAS ec Hb T BATON R Hml1 T n y Hb O overbank deposits that compose the low natural levees flanking the Mississippi River Hmm3l IBERVILLE PARISH UG Hmc3u u e Hb E P Pph yo ARIS a H H meander-belt No. 1. B Hal Hal SIPPI B SIS H Hb IS RIVER Hmc1 H a Hb M S Hml3u Hb Hb S Upper (Bayou Teche) occupation of Mississippi River meander-belt No. 3 Hb y Hcr Had Hmm3u —point-bar channel deposits associated with the relict Bayou Teche course of the Hb Hmc3u Hb ARI P ARI Mississippi River. This is the most recent meander-belt 3 occupation. il Hmd1 Hb o Hml1 N P t Crevasse complex of Bayou Teche meander-belt—silty to sandy deposits of Hmc3u Hml3u Hal O Hmc3u Hrm Hb crevasse splays originating from the Bayou Teche occupation of meander-belt No. 3. C Hmd1 Hml1 h Hb VILLE P a Hb Hmm1 NSI Hcr Hb Hml3u n E Distributary complex of Bayou Teche meander-belt—silty to clayey, natural levee Hml3u n Hcr Ppbcl e Hmd3u deposits of distributaries originating from the Bayou Teche occupation of meander-belt Hmc3u l IBER Breaux ASC No. 3. Ppbce Hb Hal Hb Hb Hcr Hal Bridge Hmd1 Natural levee complex of Bayou Teche meander-belt—silty to sometimes sandy Hml3u overbank deposits that compose the low natural levees that flank the Bayou Teche Hmc3u Hb occupation of meander-belt No. 3. Ppbe Hac Hb Hb Distributary complex occupied by the Mississippi and Atchafalaya e Hcr Hma —natural levees and abandoned course of a relict distributary system of the Bayou n Rivers Hs Ppbcl Hmm3u Hal i m Teche meander-belt. Segments of the abandoned course have been either reoccupied or Hb Hal e Plaquemine buried by distributaries of the Atchafalaya River. u Hml1 q Hml1 Had a Hb Hml3u Hml3u Hb l Lower (Bayou Portage) meander-belt of Mississippi River meander-belt No. 3 B P Hmm1 Pph Hb Hb ay Hmm3l —point bar deposits associated with the relict Bayou Portage occupation of the Mississippi Ppbce Hmd1 ou Lafayette Had River meander belt No. 3. Ppbe Hb Hal Hmc3u Hb Hmc1 Hmc3l Crevasse complex of Bayou Portage meander-belt—silty to sandy deposits of Ppbcl Hmm3l Hma Hml1 crevasse splays originating from the Bayou Portage occupation of meander-belt No. 3. Hmd1 Hac Distributary complex of Bayou Portage meander-belt—silty to clayey, natural levee Hmd3l Pph deposits of distributaries originating from the Bayou Portage occupation of meander-belt Hb Hmc3u Hml1 No. 3. Hml3u Hb Hb Hua Hua Hmm3u Hb Hb Natural levee complex of Bayou Portage meander-belt—generally silty overbank Had Hma Hal Hb Hml3l deposits that compose the low natural levees that flank the Bayou Portage meander-belt. Ppbe Hrm Hb Hmc3u Hb Hb Had Had Hml1 Hml3u RED RIVER DEPOSITS rmilio Ve n R Hb iv Hs Hml3l er Meander-belt of the Teche course of the Red River—brownish red point bar and PPI Hb ISSI R Hrm overbank deposits of the relict course of the Red River that have accumulated within the Hb Hmm1 ISS I M VE Bayou Teche occupation of Mississippi River meander-belt No. 3. Locally, these deposits Hmd3u Had R Ppav may include younger natural levee and overbank deposits of the modern Bayou Teche that Hmm1 Hb are too small to map at this scale. Hb Hal Hb Hmd1 Hmm1 Hmm1 —scattered natural Had Natural levee complex of the Teche course of the Red River A Hrl levee deposits composed of silty, reddish-brown sediments that have locally buried parts of Hb T Hb Hmm3l C the Bayou Teche natural levees. Hma H Hmc3u Hmm3l A Hb Had Major distributary channel of the Teche course of the Red River—clayey to silty F Hml1 A Hrd deposits that fill an abandoned Teche–Red River distributary along Catahoula Coulee. Hml3u L Hmd1 Hb A Hb Y Hb A Hmm3l Hal Had Hml3l Hb Hml1 PLEISTOCENE Hua Hb Hb Hb LOESS Hmd3u White Hma B Hb Peoria Loess—Eolian silt veneer of late Wisconsin age mantling Pleistocene strata. Loess A Hml1 S Castle Hb is depicted where the total thickness is 1 meter or greater. I Hb Hb N Hal Hrd rel Sor Hb Hb Hb PRAIRIE ALLOGROUP Hrm ou Had ay Hmd3u Hb B A diverse depositional sequence of late to middle Pleistocene deposits of the Mississippi Hml3l Hb M Hmd1 Had A Hmd1 River, its tributaries, and coastal plain streams; includes terraces, fluvial (meander-belt, Hua Hml3u IN Hb backswamp, and braided-stream), colluvial, estuarine, deltaic, and marine units deposited Hb over a considerable part of the late Pleistocene (Wisconsin to Sangamon). Surfaces Hb Hb Had generally show little dissection and are topographically higher than the Holocene units.