J.04_C.4_Cultural_Resources_Report_July_2005.pdf

A CULTURAL RESOURCES OVERVIEW FOR

THE RIO GRANDE AND TIJUANA RIVER

FLOOD CONTROL PROJECTS

Under contract to

United States Section, International Boundary and Water Commission

4171 North Mesa Street, Suite C-100

El Paso, Texas 79902

Contract No. IBM04D0001, Task Order No. IBM04T0015

In collaboration with

Camp Dresser and McKee, Inc.

1925 Palomar Oaks Way

Suite 300

Carlsbad, CA 92008

Submitted by

Geo-Marine, Inc.

3945 Doniphan Park Circle, Suite C

El Paso, Texas 79922

July 2005

A CULTURAL RESOURCES OVERVIEW FOR

THE RIO GRANDE AND TIJUANA RIVER

FLOOD CONTROL PROJECTS

by

Victor Gibbs, David D. Kuehn, and Christine G. Ward

Duane E. Peter Principal Investigator under contract to United States Section, International Boundary and Water Commission

4171 North Mesa Street, Suite C-100 El Paso, Texas 79902

Contract No. IBM04D0001, Task Order No. IBM04T0015.

In collaboration with Camp Dresser and McKee, Inc.

1925 Palomar Oaks Way Suite 300

Carlsbad, CA 92008

Report of Investigations No. 702EP

NMCRIS No. 93081

Geo-Marine, Inc.

3945 Doniphan Park Circle, Suite C

El Paso, TX 79922

July 2005 i

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION..................................................................................... 1-1 Project Locations..............................................................................................................1-1

Rio Grande Canalization Project Area ............................................................................1-1 Rio Grande Rectification Project Area............................................................................1-6 Presidio-Ojinaga Flood Control Project Area ..................................................................1-6 Lower Rio Grande Flood Control Project Area ...............................................................1-6 International Tijuana River Flood Control Project Area...................................................1-6

CHAPTER 2. ENVIRONMENTAL SETTING................................................................ 2-1 Physiographic Setting of the USIBWC Project Areas..........................................................2-1 Geologic Context of the USIBWC Project Areas ................................................................2-2

Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas ..........................................................................................2-2 Lower Rio Grande Flood Control Project Area ...............................................................2-4 International Tijuana River Flood Control Project Area...................................................2-9

Geomorphic Setting of the USIBWC Project Areas ............................................................2-9 Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas ........................................................................................2-10 Lower Rio Grande Flood Control Project Area (Lower Rio Grande Valley and West Gulf Coastal Plain) .............................................................................................................2-12 International Tijuana River Flood Control Project Area.................................................2-13

Soils of the USIBWC Project Areas.................................................................................2-13 Rio Grande Canalization Project and Rio Grande Rectification Project Areas .................2-13 Presidio-Ojinaga Flood Control Project Area ................................................................2-14 Lower Rio Grande Flood Control Project Area .............................................................2-14 International Tijuana River Flood Control Project Area.................................................2-14

Climatic Setting of the USIBWC Project Areas................................................................2-15 Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas .......................................................................................2-15 Lower Rio Grande Flood Control Project Area .............................................................2-15 International Tijuana River Flood Control Project Area.................................................2-16 ii

Flora and Fauna of the USIBWC Project Areas................................................................2-16 Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas .......................................................................................2-16 Lower Rio Grande Flood Control Project Area .............................................................2-17 International Tijuana River Flood Control Project Area.................................................2-18

CHAPTER 3. CULTURAL OVERVIEW........................................................................ 3-1 Rio Grande Canalization and Rio Grande Rectification Project Areas: Jornada Mogollon region ..............................................................................................................................3-1

Paleo-Indian Period.......................................................................................................3-2 Archaic Period..............................................................................................................3-2

Early Archaic Period..................................................................................................3-3 Middle Archaic Period ...............................................................................................3-3 Late Archaic Period ...................................................................................................3-4

Formative Period (A.D. 200-1450) ..................................................................................3-4 Mesilla Phase (A.D. 200-1000) ....................................................................................3-5 Doña Ana (Transitional) Phase (A.D. 1000-1250) .........................................................3-5 El Paso Phase (A.D. 1250-1450) ..................................................................................3-6

Precontact/Protohistoric Period (A.D. 1450-1581) ............................................................3-7 Historic Period..............................................................................................................3-7

Spanish Missions and the Pueblo Revolt .....................................................................3-7 Spanish Rule .............................................................................................................3-8 American Rule ..........................................................................................................3-8 International Boundary and Water Commission...........................................................3-9

Presidio-Ojinaga Flood Control Project Area: Eastern Trans-Pecos Region ........................3-10 Late Archaic Period (1,000 B.C.-A.D. 900).....................................................................3-10 Late Prehistoric (A.D. 900-1535) and Protohistoric (A.D. 1535-1700) Periods ..................3-10

Livermore Phase......................................................................................................3-11 Bravo Valley Aspect................................................................................................3-12

La Junta Phase ..................................................................................................... 3-12 Concepcion Phase................................................................................................ 3-12

Cielo Complex ........................................................................................................3-13 Historic Period (A.D. 1700-present) ..............................................................................3-13

Lower Rio Grande Flood Control Project Area: South Texas Plains ..................................3-14 Paleo-Indian Period.....................................................................................................3-15 Archaic Period............................................................................................................3-16

Early Archaic Period................................................................................................3-16 Middle Archaic Period .............................................................................................3-16 Late Archaic Period .................................................................................................3-17

Late Prehistoric Period ................................................................................................3-17 iii

Historic Aboriginal Period...........................................................................................3-18 Historic Period............................................................................................................3-18

Early Exploration ....................................................................................................3-18 Colonial Settlement .................................................................................................3-19 Tides of Change ......................................................................................................3-21 Secession and Civil War ..........................................................................................3-23 Turbulence in the Later Nineteenth and Early Twentieth Centuries .............................3-23 Irrigation on the Rio Grande .....................................................................................3-23 Levee Building on the Rio Grande ............................................................................3-24

International Tijuana River Flood Control Project Area: Tijuana River Region ..................3-24 San Dieguito Complex ................................................................................................3-25 La Jolla Complex........................................................................................................3-26 Late Prehistoric Period ................................................................................................3-26 Historic Period............................................................................................................3-27

Exploration Period (1539-1769) ................................................................................3-27 Hispanic Period (1769-1822) ....................................................................................3-28 Mexican Period 1822-1846 ......................................................................................3-29 Anglo-American Period 1846 to the Present..............................................................3-29

CHAPTER 4. PREVIOUS RESEARCH AND DATA COMPILATION.......................... 4-1

Rio Grande Canalization Project Area................................................................................4-1 Rio Grande Rectification Project Area...............................................................................4-3 Presidio-Ojinaga Flood Control Project Area......................................................................4-4 Lower Rio Grande Flood Control Project Area...................................................................4-5 International Tijuana River Flood Control Project Area ......................................................4-7 Previous Geoarchaeological Research................................................................................4-8

Rio Grande Canalization Project Area ............................................................................4-8 Rio Grande Rectification Project Area............................................................................4-8 Presidio-Ojinaga Flood Control Project Area ................................................................4-10 Lower Rio Grande Flood Control Project Area .............................................................4-10 International Tijuana River Flood Control Project Area.................................................4-11

CHAPTER 5. RESEARCH DESIGN AND DATA NEEDS ............................................. 5-1 Identification of Data Needs..............................................................................................5-1

Chronology Research Domain .......................................................................................5-2 Geoarchaeology Research Domain .................................................................................5-2 Settlement Patterns Research Domain ............................................................................5-3 Subsistence Research Domain .......................................................................................5-5 Technology Research Domain .......................................................................................5-6 Intra- and Extra- Regional Interactions Research Domain ................................................5-8 iv

Historic Era Archaeological Issues.................................................................................5-9

CHAPTER 6. SUMMARY AND RECOMMENDATIONS.............................................. 6-1 Geoarchaeological SIte Potential.......................................................................................6-1 Areas with Unknown Site Potential ...................................................................................6-3 Important Site Criteria – Data Needs .................................................................................6-4

Chronology ..................................................................................................................6-4 Settlement Patterns .......................................................................................................6-5 Subsistence Patterns......................................................................................................6-5 Technology ..................................................................................................................6-6 Intra- and Extra-Regional Interactions ............................................................................6-6 Historic Era Archaeological Issues.................................................................................6-6

Summary and Recommendations .......................................................................................6-7 The Cultural Riverine Environment................................................................................6-7 Summary of Significant Existing Resources ...................................................................6-8 Recommendations.........................................................................................................6-9 Expectation of Cultural Resources ...............................................................................6-10 Conclusions ................................................................................................................6-11

REFERENCES CITED................................................................................................... R-1

APPENDIX A. PREVIOUSLY RECORDED SITE DATA COMPENDIUM ................. A-1

APPENDIX B. COLOR KEYS TO GEOLOGIC MAPS (CHAPTER 2) .........................B-1

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LIST OF FIGURES

Figure 1.1. Project location map ..........................................................................................1-2 Figure 1.2. Project area map showing northern portion of the Rio Grande Canalization Project

Area.............................................................................................................................1-3 Figure 1.3. Project area map showing central portion of the Rio Grande Canalization Project

Area.............................................................................................................................1-4 Figure 1.4. Project area map showing southern portion of the Rio Grande Canalization Project

Area.............................................................................................................................1-5 Figure 1.5. Project area map showing the northern portion of the Rio Grande Rectification

Project Area..................................................................................................................1-7 Figure 1.6. Project area map showing the central portion of the Rio Grande Rectification Project

Area.............................................................................................................................1-8 Figure 1.7. Project area map showing the southern portion of the Rio Grande Rectification

Project Area..................................................................................................................1-9 Figure 1.8. Project area map showing the Presidio-Ojinaga Flood Control Project Area.........1-10 Figure 1.9. Project area map showing the northern portion of the Lower Rio Grande Flood

Control Project Area. ..................................................................................................1-11 Figure 1.10. Project area map showing the southern portion of the Lower Rio Grande Flood

Control Project Area. ..................................................................................................1-13 Figure 1.11. Project area map showing the International Tijuana River Flood Control Project

Area...........................................................................................................................1-15 Figure 2.1. Surface geology map of the Rio Grande Canalization Project Area........................2-3 Figure 2.2. Surface geology map of the northern portion of the Rio Grande Rectification Project

Area.............................................................................................................................2-5 Figure 2.3. Surface geology map of the central portion of the Rio Grande Rectification Project

Area.............................................................................................................................2-6 Figure 2.4. Surface geology map of the southern portion of the Rio Grande Rectification Project

Area.............................................................................................................................2-7 Figure 2.5. Surface geology map of the Presidio-Ojinaga Flood Control Project Area..............2-8 Figure 2.6. Schematic cross-section of channel avulsion in a meandering stream system (from

Walker and Cant 1984, as modified by Waters 1992:137). .............................................2-11 vi

LIST OF TABLES

Table 2.1. Soil Types Potentially Occurring within the Tijuana River Project Area (after Bowman 1973) .........................................................................................................................2-15

Table 3.1. Jornada Mogollon Regional Chronology (from Miller and Kenmotsu 2004) ............3-2 Table 3.2. Trans-Pecos Regional Chronology (from Cloud 2004; Miller and Kenmotsu 2004) 3-11 Table 3.3. Regional Chronology of South Texas (from Black 1989) ......................................3-15 Table 3.4. Regional Chronology of San Diego County...........................................................3-25 Table 4.1. Summary of Cultural Resources within One Mile of the Rio Grande Canalization

Project (n=123) .............................................................................................................4-2 Table 6.1 Previously Recorded Site Temporal Component by River Segment ..........................6-7 Table 6.2 Previously Recorded Temporal Components and Environment by River Segment ....6-8 Table 6.3. Summary of Data Needs.....................................................................................6-10 Table 6.4 Summary of Expected Cultural Resource Types...................................................6-10 vii

ABSTRACT

This document is a cultural resource overview in support of a Draft Programmatic Environmental Impact Statement (PEIS) sponsored by the United States International Boundary and Water Commission (USIBWC) for proposed projects along the Rio Grande in Texas and New Mexico, and the Tijuana River in California. Geo-Marine, Inc., conducted this work as a subcontractor to Camp Dresser and McKee under Contract No. IBM04D0001, Task Order IBM04T0015. The project summarizes previous work conducted by the USIBWC and other researchers and includes a literature review of relevant sections of 382 miles of the Rio Grande (Rio Grande Canalization Project, the Rio Grande Rectification Project, the Presidio-Ojinaga Flood Control Project, the Lower Rio Grande Flood Control Project) and five miles along the Tijuana River between the U.S.-Mexico Border and the Pacific Ocean (International Tijuana Flood Control Project.)

Site records on file at various repositories were researched to determine the nature, locations, and extent of known sites within a one-half mile corridor on each side of the river within the boundary of the United States. A total of 299 known cultural resource properties exist within these parameters. Environmental and cultural overviews provide contexts for identifying data needs and criteria for establishing National Register of Historic Places significance.

viii

ACKNOWLEDGEMENTS

This document would not have been possible without the help of a number of individuals. First, we would like to thank Daniel Borunda and Steve Fox, of the United States section of the International Boundary and Water Commission office in El Paso, Texas, for their help in obtaining needed reference documents. Duane Peter served as the principal investigator and provided valuable advice and comments on the written material. Melinda Landreth was responsible for technical editing. Martin Goetz generated the maps for the project and Sonia Padilla contributed reference formatting and data entry. We would also like to thank the Archaeological Records Management Section, the Texas Archeological Research Laboratory, and the California Historic Resources Information System for their help in providing previously recorded site data.

1-1

CHAPTER 1

INTRODUCTION

by Victor Gibbs

This document provides a cultural resource overview in support of a Draft Programmatic Environmental Impact Statement (PEIS) sponsored by the United States Section of the International Boundary and Water Commission (USIBWC) for proposed projects along the Rio Grande in Texas and New Mexico, and the Tijuana River in California (Figure 1.1). Geo-Marine, Inc., conducted this review as a subcontractor to Camp Dresser and McKee, Inc., under Contract No. IBM04D0001, Task Order IBM04T0015.

This report summarizes previous investigations undertaken by the USIBWC and other researchers. It includes a cultural resources literature review of relevant sections of 382 miles of the Rio Grande and five miles along the Tijuana River (Appendix A). Searches of site files were conducted at various repositories to determine the nature, locations, and extent of known sites in a one-half mile corridor on either side of the river within the United States boundaries. This effort resulted in the identification of 299 previously recorded cultural properties. These data, along with environmental and cultural contexts, provided the background necessary to identify substantial gaps in current archaeological understanding of sites within the USIBWC project areas.

PROJECT LOCATIONS

Four of the five flood control projects are located along the Rio Grande, from Percha Dam, just south of Caballo Lake in New Mexico, to the Gulf of Mexico. The final area is along the Tijuana River, in California. These sections are described in detail below.

Rio Grande Canalization Project Area

The Rio Grande Canalization Project Area includes a 104.5 mile -long section of the Rio Grande, beginning approximately at Percha Diversion Dam in Sierra County, New Mexico, and ending at the American Diversion Dam, in El Paso County, Texas (Figures 1.2 – 1.4). The project began in 1938 and was completed in 1943, as part of water treaty agreements with Mexico that were established on May 21, 1906. The Canalization Project provides water and flood control to the Rincon and Mesilla valleys in New Mexico, the El Paso Valley in Texas, and the Juarez Valley in Mexico. Project features within the corridor consist of 130 miles of flood control levees, 27 bridges and five dams built on adjacent arroyos between 1969 and 1975 to control sediment and flood runoff (USIBWC 2005 [website]). Several diversion dams and associated canal systems

A Cultural Resources Overview for USIBWC

1-6 exist along this portion of the river, including the Percha Diversion Dam (1914-1919), the Leasburg Diversion Dam (1906-1908), the Mesilla Diversion Dam (1914-1919), and the American Diversion Dam (1935).

Rio Grande Rectification Project Area

The Rio Grande Rectification Project Area includes an 85.6 mile -long section of the Rio Grande, beginning at the American Diversion Dam in El Paso County, Texas, and ending near Fort Quitman, Hudspeth County, Texas (Figures 1.5 - 1.7). The project began with the signing of the Rio Grande Rectification Treaty between the United States and Mexico on February 1, 1933, and was completed in 1938. During the project, the segment of the river was shortened from 155.2 miles to 85.6 miles. Significant diversion features along this segment of the river include the American Diversion Dam (1935), the International Dam, the Franklin Canal (1889-1890, 1914- 1915), and the Riverside Dam.

Presidio-Ojinaga Flood Control Project Area

The Presidio-Ojinaga Flood Control Project Area consists of a 15-mile section of the Rio Grande, six miles upstream and downstream from the sister towns of Presidio, Presidio County, Texas, and Ojinaga, Chihuahua, Mexico (Figure 1.8). The flood control project, which consisted of river straightening and levee construction, was completed in 1975 (Holiday and Ivey 1974).

Lower Rio Grande Flood Control Project Area

The Lower Rio Grande Flood Control Project Area (LRGFCP) extends from Penitas, Hidalgo County, Texas to the eastern portion of Cameron County where the Rio Grande empties into the Gulf of Mexico (Figure 1.9 and 1.10). Offstream channels in these two counties as well as Willacy County may be affected by future construction activities. The project area consists of 180 winding river miles. Features within the LRGFCP include 270 miles of levees, Retamal and Anzalduas dams, the Morillo Drain, and 500 irrigation and drain structures (USIBWC 2005 [website]).

International Tijuana River Flood Control Project Area

The International Tijuana River Flood Control Project Area (ITRFCP) consists of an approximately five-mile segment from the International Boundary to the Pacific Ocean, in San Diego County, California (Figure 1.11). The ITRFCP was completed in 1979. Specific proposed construction activities for this part of the project area were outlined within the scope of work.

These activities are focused along a 2.3-mile segment of the Tijuana River, including construction of:

a) 1,223-foot long (0.23 mile) concrete channel,

b) 3,700-foot (0.70 mile) flared energy dissipater with grouted stone

c) 7,021-foot (1.33 mile) unlined low-flow channel;

d) 5287-foot (1.0 mile) levee on north side of channel;

e) 2,565-foot (0.49 mile) levee on the south side of the channel.

2-1

CHAPTER 2

ENVIRONMENTAL SETTING

by

David D. Kuehn

This chapter summarizes the physiographic, geologic, climatic, and biotic settings of the five USIBWC project areas. The individual characteristics of the natural landscape are highly varied and are, in part, a product of the dynamic relationships that exist between climate, vegetation, and geomorphology. Geologic structural activity has also greatly influenced the physiographic and geomorphic development of large portions of the USIBWC areas.

PHYSIOGRAPHIC SETTING OF THE USIBWC PROJECT AREAS

The five USIBWC flood control projects are located in a variety of different physiographic regions. The Rio Grande Canalization Project (Percha Diversion Dam in New Mexico, to the American Diversion Dam in Texas), Rio Grande Rectification Project (American Diversion Dam to Fort Quitman, Texas), and the Presidio-Ojinaga Flood Control Project (Presidio County, Texas) areas are all located in the Basin and Range physiographic province (Muhs et al. 1987;

Dohrenwend 1987), while the Lower Rio Grande Flood Control Project is situated in the West Gulf Coastal Plains physiographic province (Walker and Coleman 1987). The International Tijuana River Flood Control Project is located in the Tijuana River Basin and wave cut coastal plain portion of the Peninsular physiographic province.

The Basin and Range province covers a large portion of the western and southwestern United States (U.S.) and is characterized by parallel to sub-parallel-mountain ranges (horsts) separated by generally elongated basins (grabens). The Canalization, Rectification, and Presidio-Ojinaga Flood Control Projects are located within the Rio Grande Rift region, an area comprised of a series of asymmetrical grabens created by crustal extension and lithospheric thinning.

The West Gulf Coastal Plain physiographic province includes the western portion of the Gulf of Mexico coast and is characterized by sea-ward dipping layers of marine sediments (Cretaceous- Quaternary) overlain in places by fluvial/deltaic deposits, which are largely Quaternary in age (Walker and Coleman 1987:53). The Lower Rio Grande Flood Control Project area is situated within the Rio Grande flood and deltaic plain, an area comprised of sinuous stream channels and numerous abandoned drainage channels (resacas), meander scars, and oxbow lakes (bancos).

The Peninsular physiographic province is part of the Pacific Coast and Mountain geomorphic system (PCMS). The PCMS is characterized by coastal mountains and plains that front the Pacific Ocean from the U.S.-Mexico border through Alaska. The Peninsular province is located in the southern portion of the PCMS and includes the distal end of the Tijuana River basin, which

2-2 is characterized by wave-dominated coastal plains and alluvial and estuary/marine-margin depositional environments.

GEOLOGIC CONTEXT OF THE USIBWC PROJECT AREAS

Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas

The geology of the areas that encompass the Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project areas are inexorably tied to the geologic history of the Rio Grande Rift and Mexican Highlands portion of the Basin and Range province. The formation of the Basin and Range province began with the deformation of late Precambrian and Paleozoic continental margin strata during late Paleozoic to early Mesozoic orogenies. Deformation included two episodes of middle to late Cenozoic extensional faulting (Stewart 1978, 1980). Early detachment faulting began between circa (ca.) 30 and 35 Ma (million years ago) while the high-angle block faulting that is today a classic feature of the Basin and Range was initiated at ca. 17 Ma (Christiansen and McKee 1978; Dohrenwend 1987; Eaton 1982). In the Rio Grande Rift, this deformation continued in episode fashion to the present day (Dohrenwend 1987).

The tensional processes responsible for creation of the Rio Grande Rift resulted in a long, fairly narrow valley dominated by a series of north-south asymmetrical basins (Chapin and Cather 1994; Halley 1978). These basins are dominant features of the Rio Grande valley from southern Colorado downstream to near Presidio, Texas. There are four staggered, joined basins in the southern Colorado and New Mexico portions of the Rift. These are, from north to south, the San Luis Basin, The Espanola Basin, the Albuquerque (or Middle Rio Grande) Basin, and the Mesilla Basin.

South of the Albuquerque Basin, the rift valley broadens and is comprised of a series of angled mountain ranges and intervening basins. This portion of the Rift Valley is physiographically similar to the adjacent Basin and Range province but is differentiated by more active faulting during the Pliocene and Pleistocene, the presence of deep basins, and volcanic activity during the late Quaternary (Chapin and Cather 1994; Veach 1998).

In the New Mexico portion of the Rio Grande valley, surface geologic units include Quaternary alluvium and dune sand, the Tertiary and Quaternary Santa Fe Group (including the Camp Rice Formation), Quaternary basalt flows, Tertiary-aged volcanics (Rubio Peak and Palm Park Formations, Orejon andesite, and intermediate to silicic intrusions), and undivided Paleozoic (New Mexico Geological Society 1982; Figure 2.1, map color key is in Appendix B).

Quaternary alluvium is concentrated in the Rio Grande floodplain and on adjacent terraces and alluvial fans. The alluvium is comprised of largely unconsolidated gravels, sands, and muds of Pleistocene and Holocene age. In the Albuquerque Basin, Connell and Love (2001) describe six lithostratigraphic units within the Rio Grande valley that are inset against the Plio-Pleistocene deposits of the Santa Fe Group (which is ancestral Rio Grande valley fill). These units are, from oldest to youngest, the Lomatas Negras, Edith, Menaul, Los Duranes, Arenal, and Los Padillas Formations (Connell and Love 2001:J-67). Along the western edge of the Rio Grande valley, the surface of the Lomatas Negras Formation (or its temporal/lithological equivalent) is situated 65 to 75 m above the modern Rio Grande floodplain. The unit is comprised of moderately consolidated gravel (Connell and Love 2001:J-68). The Edith Formation is composed of upward-fining gravel, sand, and mud. The base of the 3-12 m thick unit lies ca. 12 to 24 m above the floodplain

2-4 of the Rio Grande. The Los Duranes Formation was originally defined by Lambert (1968) and consists of 40-52 m of terrace fill in the form of reddish-brown to yellowish-brown sand, gravel, and sandy clay. The tread of the Los Duranes terrace lies about 42-48 m above the Rio Grande floodplain near Bernalillo, New Mexico (Connell and Love 2001). The Menaul and Arenal Formations are composed of gravel and gravelly sand and are located 26-36 and 15-21 m above the Rio Grande, respectively. The youngest fluvial unit described by Connell and Love (2001) is the Los Padillas Formation, which corresponds to the fill of the Rio Grande floodplain. The Los Padillas Formation (or its equivalents) is 15 to 24 m thick and consists of unconsolidated, pale brown sand, gravel, and interbedded, fine-grained sand, silt, and clay (Connell and Love 2001:J- 73). The aggradation of the Los Padillas Formation began after the last glacial maximum, which occurred between ca. 15,000 and 22,000 years ago. Aggradation of the floodplain fill continued throughout the Holocene; however, most of the formation sediments were deposited prior to ca.

4500 years B.P. (Connell and Love 2001).

There are six structural basins along the Texas portion of the Rio Grande Rift. From north to south, these are the Mesilla Basin, the Hueco Bolson, the Salt Basin, the Eagle Basin, the Red Light Basin, and the Presidio Basin (Ryder 1996). A seventh basin, the Redford Bolson, is located south of Presidio, Texas and is considered a southern extension of the Presidio Basin.

Surface geologic units along the Texas portion of the Rio Grande Rift from American Dam to Fort Quitman are dominated by Quaternary-aged alluvium. These deposits include Qal (young Quaternary alluvium-Holocene), Qao (old Quaternary alluvium-Pleistocene), Qs (Quaternary sands), and Qtb (Quaternary-Tertiary Bolson Formation). Near the Rio Grande in the El Paso area, older rocks outcrop in the Franklin Mountains. These include Permian, Paleozoic, Ordovician, and Eocene deposits (Texas Bureau of Economic Geology 1992) (Figures 2.2 – 2.4;

see Appendix B for map color key).

In the Presidio-Ojinaga Flood Control Project area, the Rio Grande has down cut through primarily Oligocene, but also Eocene-aged, volcanic rocks and conglomerates. These are labeled on the Geologic Map of Texas as OE, “Oligocene and Eocene undivided” (Texas Bureau of Economic Geology 1992). In the same immediate project area, the valley walls, according to the Emory Peak-Presidio Sheet of the Geologic Atlas of Texas, are comprised of the Oligocene Fresno Formation, a complex unit that includes volcanic breccias, tuffs, tuffaceous sandstone, and conglomerates (Barnes 1979, as summarized in Abbott 2001:109) (Figure 2.5; see Appendix B for map color key.

Lower Rio Grande Flood Control Project Area

The surface geology in the Lower Rio Grande Flood Control Project area is dominated by Quaternary-aged clays, silts, sands, and gravels that are primarily alluvial in origin, with lesser amounts of eolian, delta front, and near-shore deposits. Some of the latter types of sediments were originally deposited as alluvium that was later reworked by non-alluvial processes. The Quaternary deposits are unconformably underlain by Tertiary-aged marine sediments.

Bedrock geology in the Lower Rio Grande valley is characterized by late Cretaceous and Tertiary units that dip gently to the east-southeast. The oldest unit in the region is the Tertiary Goliad Formation (Pliocene), which has a thickness of ca. 180 m and is comprised of Pliocene sandstones, marls, and limestones associated with marine and marine-margin environments. The Pliocene sediments are fluvial-deltaic in origin. The oldest Pleistocene units are represented by the Lissie and Beaumont formations. The Lissie Formation consists of up to 120 m of fluvial sediments deposited by meandering channels of the ancestral Rio Grande. These sediments represent point bar, channel, oxbow lake, and backswamp depositional environments (Brown et

al. 1980:47-54; Day et al. 1981:6). The Beaumont Formation units have a maximum thickness

Chapter 2. Environmental Setting

2-9 of ca. 275 m and outcrop over expansive areas north of the current Rio Grande floodplain. The lower Beaumont Formation consists of deltaic sediments arranged in stacked vertical sequences of distributary channel and levee sands, and interdistributary muds associated with seaward-extending lobes of the ancestral Rio Grande delta (Brown et al. 1980). The upper Beaumont Formation consists of Pleistocene fluvial-deltaic sediments deposited during Wisconsin interglacial episodes. These deposits are separated from the lower Beaumont units by an erosional unconformity and are termed Raymondville by Brown and others (1980).

International Tijuana River Flood Control Project Area

The 5.3-mile long ITRFCP area encompasses the Tijuana River Valley and Estuary in the Coastal Plains portion of the Peninsular Ranges province of southern California. The Peninsular Ranges province is characterized by a low-relief coastal plain, wave-cut marine terraces (mesas), and a series of elongate mountain ranges. The latter “formed when granites intruded into older metamorphics and sediments” (Moratto 1984:18). The “backbone” of the Peninsular Ranges consists of the Southern California batholith (Christenson 1990; Larsen 1954), a large mass of plutonic rock intruded into the older sediments (Jahns 1954). Elevations in some areas of the province approach 1,830 m (6,000 ft) above mean sea level (amsl).

The Coastal Plains portion of the Peninsular Range province is dominated by a series of fairly smooth marine terraces locally known as mesas. These mesas are composed of Pleistocene and Upper Pliocene marine deposits known as the Lindavista, Sweitzer, and San Diego formations (Biehler 1979) and are often dissected by steep-sided canyons and smaller drainages. The elevation of the mesas ranges from sea level to about 244 m (800 ft) amsl (Bowman 1973). Otay Mesa covers a large portion of southern San Diego County. It is bordered on the west by the Tijuana River valley, which flows from Mexico into the Pacific Ocean, and on the east by the foothills of the San Ysidro Mountains. A series of smaller mesa tops that lie primarily in Mexico extend north over the border on the western end of the project area, the largest of which is Spooner’s Mesa. Spooner’s Mesa is located approximately 1.45 km (0.9 mi) from the Pacific Ocean; Spooner’s and Otay mesas are separated by the Tijuana River valley. Several major drainages bisect the mesa tops; Goat Canyon and Smuggler Gulch drain Spooner’s Mesa from southeast to northwest, and Spring and Wruck canyons drain Otay Mesa from northeast to southwest; all drain into the Tijuana River valley.

Surface geologic units in the ITFLP area include recent (i.e., Late Quaternary) alluvium, slopewash, deltaic/estuary deposits, littoral beach sands, and sand dunes. Littoral sediments dominate the coastal portion of the project area, while alluvial deposits become dominate ca. 1.5 km east of the modern coast. Alluvial sandy soils flanking the Tijuana River channel have been termed the Tujunga sands (Butler/Roach 1988; Higgins et al. 1994a). Holocene deposits in the Tijuana River floodplain/estuary are ca. 30 m thick. These overlie, and/or are adjacent to sandstones and conglomerates of Pliocene to late Pleistocene age (U.S. Army Corps of Engineers 1989; Higgins et al. 1994a).

GEOMORPHIC SETTING OF THE USIBWC PROJECT AREAS

The geomorphology, or surface landform configuration, of the USIBWC project areas closely parallels their physiographic setting, again because of the direct relationship between climate, vegetation, and landforms (cf. Ritter 1978:18-21). Within the Rio Grande Rift Valley, the geologic/structural history of the region has directly influenced the geomorphology of the

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USIBWC project areas, while in the Tijuana River and Lower Rio Grande valley, surface landform development has been shaped by a combination of fluvial and marine-margin processes.

Rio Grande Canalization Project, Rio Grande Rectification Project, and Presidio-Ojinaga Flood Control Project Areas

The Rio Grande is an extremely diverse perennial river that heads in the San Juan Mountains of south-central Colorado and from there, extends south through the central portion of New Mexico and the Rio Grande Rift, before trending south-southeast along the United States/Mexico border.

The river eventually debouches into the Gulf of Mexico near Brownsville, Texas. With a length of approximately 3,200 km, and with elevations ranging from over 10,000 ft to sea level, the Rio Grande exhibits tremendous variability in local geomorphic conditions. In the Rift Valley region, the latter include channel sinuosity and hydraulic geometry, suspended and bedload competence, bank stability, and gradient adjustment (Schumm 1968; Schumm and Lichty 1965).

In narrow portions of the Rio Grande valley, the prehistoric channel of the Rio Grande followed a generally braided pattern; in broader portions of the valley, it assumed a sinuous, meandering pattern. While structure and bedrock controlled much of the geomorphic development of the confined portions, meandering and avulsion dominated the geomorphic processes in the broad valley portions. Other characteristics such as sediment load have also been heavily influenced by proximity to tributary streams. Finally, human modification of the Rio Grande floodplain has been dramatic and has resulted in significant alterations to the natural physiographic, geomorphic, and biotic landscape. These developments include dams and reservoirs, channelization, levee construction, channel stabilization and diversions. Cumulatively, the modifications have served to greatly reduce sediment yield to downstream portions of the river valley. This, in turn, has led to changes in geomorphic activity within the Rio Grande channel such as the number and movement of sand bars, altered thalweg positions, and migration of the channel across the valley floor (Tetra Tech 2004:13). In addition, reduction in activity within the channel leads to the stabilization of sandbars because frequent inundation does not remove anchoring vegetation.

Processes such as this greatly influence the geomorphic characteristics of the river channel and adjacent floodplain.

Significant natural changes to the Rio Grande floodplain have occurred repeatedly during the Holocene due to stream meandering, flooding, and channel avulsion. One example of the diversity associated with adjustments to the Rio Grande channel was evident during an analysis of the fluvial activity over a 68-year period, between 1844 and 1912, in segments of the river through the Hueco Bolson and Mesilla Basin (Mack and Leeder 1998). According to a study conducted by the Bureau of Reclamation and other map sources from the period, the following channel and valley-bottom modifications were historically documented:(1) the width of the channel varied between 100-1,330 m; (2) sinuosity ranged from 1.2-1.9 (Schumm 1963); (3) portions of the channel migrated laterally over distances in excess of 1 or 2 km (in both straight and meandering segments); (4) a number of areas underwent sudden episodes of meander loop cutoff; and (5) different portions of the Mesilla Basin experienced at least three major episodes of channel avulsion (Mack and Leeder 1998).

Avulsion is a process involving the abandonment of a former river channel and the establishment of a new channel during high-energy flood events (cf. Walker and Cant 1984; Waters 1992).

Geomorphic research indicates that portions of the Rio Grande floodplain are very prone to avulsion and indeed avulsion events are noted in historical accounts of the river's activity (Mack and Leeder 1998). Avulsion is initiated in five stages: (1) oxbow lakes are created through neck and chute cutoff of meander loops; (2) the lakes become filled with overbank muds, which form “clay plugs”; (3) the clay plugs are highly cohesive and resistant to erosion, which restricts the

2-11 lateral migrations of the channel to a narrow, sandy meander belt; (4) channel, point bar, and levee deposition within the meander belts results in the construction of an alluvial ridge that rises above the level of the surrounding floodplain; (5) natural levees on this ridge are breached during a high energy flood event and runoff is funneled to the lowest portion of the floodplain, resulting in the establishment of a new channel and the abandonment of large portions of the former channel (Walker and Cant 1984; Waters 1992:137-138). As illustrated in Figure 2.6, avulsion-prone rivers leave numerous oxbow lakes and “clay plug” deposits.

Figure 2.6. Schematic cross-section of channel avulsion in a meandering stream system (from Walker and Cant 1984, as modified by Waters 1992:137).

Because of research conducted in conjunction with the Desert Project, Gile and others. (1981) identified Pleistocene and Holocene deposits within the Rio Grande valley. These are termed the Tortugas, Picacho, and Fort Seldon units and include piedmont, alluvial fan, and terrace environments. The Fort Seldon unit is further subdivided into the Leasburg and Fillmore members, the former represent swath terrace and graded fan surfaces and date to ca. 9000 yr B.P.

(Hawley 1965; Gile et al. 1981; Metcalf 1969).

As previously stated, Connell and Love (2001) have estimated that aggradation of the Rio Grande floodplain (termed the Los Padillas Formation) in the Albuquerque Basin occurred from the late Pleistocene through most of the Holocene. Radiocarbon dates from floodplain and adjacent alluvial fan deposits in the area from Percha Dam to south of El Paso were obtained and reported by Brown and others (2001), Frederick and Higgins (1993), Gallison and Wilcox (2001), and Hall (1994). The oldest dates out of the 11 reported by Brown and others (2001:102-104) were derived from Btbk soils in alluvial fan and arroyo mouth settings; these dates were 4850±70 yr

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B.P. and 3070±60 yr B.P., respectively. The remaining samples, from Rio Grande sediments in the Rincon and lower Mesilla valleys, dated between 1090±60 and 260±60 yr B.P. (Brown et al.

2001:104). An additional 40 radiocarbon dates from the lower Rio Grande floodplain were reported by Frederick and Higgins (1993) and Hall (1994). These are summarized in Brown et al.

(2001:105-107) and span the period from ca. 7300 to less than 100 yr B.P. The dated samples were recovered from primarily Rio Grande floodplain sediments and soils, but some were collected from adjacent, often interfingering, alluvial fan and arroyo sediments. While the range of ages reported from these samples is in keeping with the Late Pleistocene/Holocene age estimates for the equivalent Los Padillas Formation in the Albuquerque Basin, most of the dates were derived from bulk organic sediments. Bulk sediment dating has proven problematic by numerous researchers; with the problems associated with the inability to account for the source of organic carbon in soils (cf. Wang et al. 1996). These potential problems were addressed by Frederick and Higgins (1993), who argue that the soil humate ages may include older carbon stored in upstream alluvial fill, resulting in ages that are older than the actual episodes of valley aggradation. Brown and others (2001:108) on the other hand, argue that many of the humate ages are internally consistent and correspond well with temporal estimates provided by diagnostic archaeological materials.

This question is also addressed by Cooper and others (2003), who summarize geoarchaeological investigations conducted in the Lower Rio Grande Flood Control project area. The investigations centered on the excavation of backhoe trenches from floodplain localities located between Penitas and Brownsville, Texas.