Visualizing Texas Parent Materials Julieta Collazo, Jonathan Gross, Cristine L. S. Morgan Agrilife Research, Texas A&M University, College Station, TX

Figure 2: INTRODUCTION Water MAJOR LAND RESOURCE AREAS A parent material map for Texas was created Wind Blown PARENT MATERIALS OF TEXAS SOIL to further the ISEE2 goal of better visualization Aeolian Sand for teaching soil science. Texas has a diverse Loess depositional history which includes residuum, as Coastal Sediments well as water and wind transported materials Coarse Coastal Sediments (Fig. 1). The most difficultly was found in Fine Coastal Sediments differentiating alluvial sediments in the Coastal Plains. While these materials were classified Young Alluvium similarly by the United States Department of Old Alluvium Agriculture, differentiation of the two processes Deltaic Alluvium is important for teaching purposes. Another Lacustrine Alluvium 42 Desertic Basin problem that was encountered in the decision 77 High Plains 85 Grand Prairie Valley Fill Alluvium 78 Central Rolling Red Plains making process was delineating general 86 Blackland Prairie Alluvial Fans 80 Prairies 87 Claypan 81 Edward Plateau categories that are instructive for land use Undifferentiated Residuum 133 Coastal Plain 82 Central Basin 150 Gulf Coast Prairie decisions. Residuum Clastic 83 Rio Grand Plains and Valley 151 Gulf Coast Marshes 84 Cross Timbers Residuum Igneous or Metamorphic 152 Gulf Coast Flatwoods The overall goal of this project was to develop a Residuum Tuff decision tree to convert Official Series Colluvium Figure 3: 1st ORDER CLASSIFICATION Descriptions (OSD) to parent materials, to aid Organic Material teaching, as well as be congruent with Anthropogenic Windblown material, neighboring states and the United States. No Data reworked or deposited by AEOLIAN wind? METHODS In coastal MLRA 83, 86-87,  Texas has 1553 OSDs, and a diverse range 133, 150-152 and COASTAL in depositional history (Fig. 1). residuum, marine, or SEDIMENTS coastal terrace?  Texas has 15 Major Land Resource Areas (MLRA) (Fig. 2). A terrace, floodplain, playa lake, bajada, valley, apron, ALLUVIUM  First order classification of each OSD was escarpment, or fan? based on the MLRA and series site description (Figs. 2 & 3). Contains R/Cr OR developed from residuum, , chert,  Second order classification refined the RESIDUUM conglomerate, igneous or source of material (Fig. 4). metamorphic rock, or ash non-crystalline tuff?  Lastly, grain size (coarse or fine) and the Does it state it is colluvium? chemistry (basic or acidic) were classed out. COLLUVIUM Was it deposited by gravity?

Figure 1: TEXAS LITHOLOGY Is it a peat bog or Histosol ORGANIC Chert/Dolomite OR have an O horizon? MATERIAL Clastic 1 /Mudstone 2 Mining, urban land, levee ANTHROPRO Evaporite OR other man-made GENIC feature? Igneous 8 Soil Morphology & Interpretations Class Limestone 3 Parent Material Field Trip Metamorphic 4 1. Stop to see 5th Terrace of Brazos river being mined for sand Mudstone Figure 4: SECONDARY CLASSIFICATIONS Old Alluvium Coarse Acidic Sand 2. Stop to texture soil in the Brazos river floodplain AGE, Floodplain, Valley, Young Alluvium Fine Basic Shale LANDFORM, Bajada, rd LOCATION Escarpment, etc 3. Stop to see Vertisol of 3 Brazos river terrace Tuff Old Alluvium Fine Basic Coarse or Fine GRAIN SIZE 7 4. Transition from terrace to coastal sediments (vegetation change) Grained Coastal Sediments Fine Uncemented Basic 5. Outcrop of sandstone, siltstone, and lignite from coastal sediments CHEMISTRY Acidic or Basic 5 Coastal Sediments Fine Weakly Cemented Acidic 6. Volcanic ash, reworked by water Residuum Tuff Fine Acidic ACKNOWLEDGEMENTS 6 7. Drop from terrace to floodplain This project is funded by the Cooperative State Research, 8. Oxbow from old river channel Education, and Extension Service, U.S.D.A. Award No. 2013- 70003-20924. Special Thanks to Dr. C. Tom Hallmark for advice Young Alluvium Coarse Basic on setting up classifications and to Dr. Darrell G. Schulze for project leadership.