Iversity: of Texas Bulletin 234:0: October 22, 1923 GEOLOGY AND MINERAL RESOURCES OF MCLENNAN COUNTY BY W. S. ADKINS BUaSAU OF ECONOMIC GEOLOCrY AKD TECHKrOX.OGU" BIVISSOH Or SCO2TOMZC &EOIOGY J. A. .UDDEN, Director of the Bureau and Head of the Division PUBLISHED BY THE UNIVERSITY OF TEXAS AUSTIN 8144-923-2500 University of Texas Bulletin No. 2340: October 22, 1923 GEOLOGY AND MINERAL RESOURCES OF MCLENNAN COUNTY BY W. S. ADKINS BUREAU OF ECONOMIC GEOLOGY AND TECHNOLOGY DIVISION OF ECONOMIC GEOLOGY J. A. UDDEN, Director of the Bureau and Head of the Division PUBLISHED BY THE UNIVERSITY FOUR TIMES A MONTH AND ENTERED AS' SECOND-CLASS MATTER AT THE POSTOPFICE AT AUSTIN, TEXAS, UNDER THE ACT OF AUGUST 24, 1912 The benefits of education and of useful knowledge, generally diffused through a community, are essential to the preservationof a free govern- ment. Sam Houston. Cultivated mind is the guardian genius of democracy. It is the only dictator that freemen acknowl- edge and the only security that freemen desire. Mirabeau B. Lamar. Contents Page Introduction 7 Physiography and Topography 9 Drainage 11 Bosque Escarpment 12 Physiographic Divisions 13 Base map 13 Magnetic station 15 Precise levels 17 Elevations " 18 The Geologic Section 19 Pre-Cambrian (?) 25 Paleozoic 25 Comanchean (Lower Cretaceous) 28 Trinity Division 28 Basal sands 28 Glenrose formation 29 Equivalents of the Paluxy sand 30 Predericksburg Division 30 Walnut formation 30 Comanche Peak formation 32 Edwards formation 33 Washita Division 38 Georgetown formation 38 Del Rio formation 46 Buda formation— 52 The Comanchean Upper Cretaceous Contact 52 Upper Cretaceous 67 Woodbine formation 67 Eagleford formation 67 Austin formation 79 Taylor formation 82 Cenozoic and Recent 83 High Upland Gravels 83 River terraces 84 Structural Geology 86 Economic Geology 92 Oil and Gas 92 South Bosque Oil Field 93 Other structural possibilities 98 Water 99 Artesian water 99 Surface wells 100 Springs 101 4 University of Texas Bulletin Page Stream water 101 Impounded water 101 Hot and mineral waters 102 Clay Industries 106 Brick 106 Tile and pottery 107 Bentonite 107 Lime Industries 107 Portland cement 107 Road materials 110 Building materials 112 High purity limestone 112 G.ravel and Sand 114 Terrace deposits 114 River bottom deposits 114 Soils 115 Building foundations 116 Well data 116 Bibliography 17 8 List of flowering plants in McLennan 'County, by Dr. Lula Pace. .183 Index 199 Illustrations PLATES Plate 1. Geologic map of McLennan County, Texas. (Inside Back Cover). Plate 2. Edwards and Comanche Peak limestones on Bluff Creek, at crossing of Crawford-Coryell City road. Plate 3. (a) Georgetown formation on Middle Bosque River,near China Springs. (b) Fault at Austin-Taylor contact, Waco Creek and 11th Streets, Waco. Plate 4. (a) Del Rio-Eagleford contact at locality 966, between McGregor and Moody. (b) "Bosqueville rock" (Buda) in Keyes' Branch at Bosqueville. FIGURES Page Figure 1. Map of Texas showing location of McLennan County and of Lower Cretaceous and Upper Cretaceous outcrops 8 Figure 2. The physiographic divisions of McLennan County. 10 Figure 3. The geologic column in McLennan County 21 Figure 4. North-south changes in the Comanchean formations near McLennan County 23 Figure 5. Map of Bosqueville region 59 Figure 6. Relations of Buda and Woodbine formations in McLennan County 65 Figure 7. Profiles across the Bosque Escarpment 69 Figure 8. Correlation of well logs in McLennan County 91 Figure 9. Approximate contours on the Edwards Limestone. 91 Figure 10. Map of the South Bosque Oil Field 96 The geology and mineral resources of McLennan County BY W. S. ADKINS Introduction McLennan County is situated in Central Texas somewhat east of the geographic center1 of the State. The county is practically rectangular with its greatest length running N. 60 E., following the original Spanish leaguelines, and has, an area of about 1041 square miles. It is in the zone of densest popu- lation of the State, having a population of 82,921 (1920 cen- sus). The county is located far enough south to escape the severity of the northers, a,nd on the wilole has, an equable climate; the mean annual temperature is 67° ;the mean an- nual rainfall is 22.77 inches, The elevations of the surface range from about 950 feet in the west corner to about 350 feet where the Brazos River leaves the county. The magnetic declination in December 1921. was 9° 04/ East, and is increasr ing at the rate of 3 minutes per year. The county seat of McLennan County is Waco (elevation- 414 feet2 ; population, official estimate, March, 1923, 41,626; 1920 census, 38,500). The city of Waco occupies the site of two Indian villages, El Qu'scat and Flechazos, which in the latter part of the eighteenth century were occupied by the agricultural Waco (Tawa,koni) Indians. The main village in 1824 had a population of about 100 men, according to Stephen F. Austin. Numerous remains from these villages have,- been Manuscript submitted July, 1923, published January, 19 24. The writer studied the Bosqueville area in March, 1919; the geologic county map was made during October— December, 1921. Iam greatly indebted to Dr. J. A. Uclden for valuable suggestions and for informa- tion on the subsurface geology; and to Dr. R. T. Hill and Dr. Lula Pace for their kind assistance on various questions. Many persons have generously supplied well data an,d samples. Mr. Baker Hoskins assisted in some of the later field work. 2See table of precise levels in McLennan County. 8 University of Texas Bulletin found, and earthworks were extant until recently. (See: F. W. Hodge, Handbook of North American Indians north of Mexico, Brair. Am. Eth., Bull. 30, pt. 2, p. 888, 1910). A white settlement was earlyestablished at Waco Springs on the Brazos. In 1850 McLemnan County was formed from parts of Navarro, Limestone and Falls Counties, Some com- munities, as Bosqiueville, antedate considerably the Civil War, Fig. 1. Map of Texas, showing location of McLennan County and of Lower Cretaceous and Upper Cretaceous outcrops. but in the readjustment following the building of railroads, Waco was favored by topographic advantage, and became the most important town in the county. Waco is the center of a rich farming country, and lies on the main line of automobile .and rail travel from north to south Texas, so that its, radius of economical transportation is siumciently large to assure it of ;a. trade territory covering much of Central Texas. Geology and Mineral Resources of McLennan County 9 Physiography and Topography McLennan County lies in an eastward sloping coastal plain country underlain by eastward dipping- Lower and Upper Cre- taceous rocks. : The entire county is drained directly or indirectly by the Brazos River, which cuts across the county 'from, northwest to southeast. The Brazos winds through a. broad flat alluvial covered valley which varies from one to fou.ir miles in width, and in the west part of the county lies as much as 250 feet below the adjacent uplands. In the northwest part of the county where the formations cut through by the river consist largely of hard beds, mainly limestone, the valley is narrow and is bordered by cliffs, but in the southeast part of the county, where the softer Upper Cretaceous beds occur, fresh exposures are rarer and the valley floor is largely mantled by flood plain deposits. The largest lateral of the Brazos is the Bosque River. This flows east of north and empt:es into the Brazos about 3 miles above Waco. The Bosque follows very closely the boundary between +he Lower and Upper Cretaceous formations and over most of its course skirts the west base of a long line of west facing cliffs, the Bosque Escarpment, Th's escarpment continues north of the Brazos along the east side of Aquilla Creek, and enters Hill County just north of Tokio; it thus divides the county roughly into halves, the part east of it comprising the Black Prairie (Upper Cretaceous) and the part west of it the ■ Grand Prairie (Lower Cretaceous). The west branches of the Bosque River are the North Bosque, Hog Creek and the Middle Bosque. They arise as long straight laterals from the highlands in Bosque and Coryell Counties which form the divide between the: Leon and Bosque Rivers and descend towards the southeast, following very nearly the dip of the underlying formations. As they approach the Bb-sque River1, they cut rather1 deep, valleys so that, their lower courses are separated by broad erosional divides.1 The county includes three portions of the East Central Province of Texas: (a) the Lampasas Cut-Plain, (b) the Grand Prairie, and (c) the Black Prairie. Of these, the 10 University of Texas Bulletin Lampasas! Cut Plain occupies only a small area in the west corner of the county, from Crawford to Valley Mills, which is a cont'nuation of the typical Coryell Coiuoxty topography and forms the extreme eastern edge of the Cut Plains ; this region is underlain by rocks of the Frederieksiburg division of the Lower Cretaceous. The Grand Prairie includes the dis- sected uplands west of the Bosque, around McGregor, and a Fig. 2. The physiographic divisions of McLennan County small area north of the Brazos, near Gholson, and is under^ lain by rocks of the Washita division of the Lower Cretaceous. The Black prairie includes the "black land" country, cast of the Missouri, Kansas and Texas Eailway, and is underlain by Upper Cretaceous formations. Dare to the practical absence of Woodbine outcrops of the sandy facies in Mc- lennan County the Eastern Cross Timbers area is not repre- sented in the county.