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Nebraska Department of Environmental Quality Appendix E Resource-Specific Data January 2013 Nebraska’s Keystone XL Pipeline Evaluation Nebraska Department of Environmental Quality Appendix E.1 Geology Technical Memorandum January 2013 Nebraska’s Keystone XL Pipeline Evaluation Nebraska Department of Environmental Quality TABLE OF CONTENTS A p p e n d i x E . 1 Geology Technical Memorandum ..................................................... E.1-1 E.1.1 Existing Conditions ..................................................................................................................... E.1-1 E.1.1.1 Landscape .................................................................................................................. E.1-1 E.1.1.2 Geologic History of High Plains ............................................................................. E.1-1 E.1.1.3 Geology of Nebraska ............................................................................................. E.1-3 E.1.1.4 Bedrock Geology of Nebraska Reroute .............................................................. E.1-7 E.1.1.5 County Geology ....................................................................................................... E.1-8 E.1.1.6 Mineralogical Resources .......................................................................................... E.1-9 E.1.1.7 Paleontological Resources ....................................................................................... E.1-9 E.1.1.8 Geologic Hazards ................................................................................................. E.1-10 E.1.2 Potential Impacts ..................................................................................................................... E.1-12 E.1.2.1 Topography ............................................................................................................ E.1-12 E.1.2.2 Mineralogical Resources ....................................................................................... E.1-12 E.1.2.3 Paleontological Resources .................................................................................... E.1-13 E.1.2.4 Geologic Hazards ................................................................................................. E.1-13 E.1.3 Mitigation ................................................................................................................................. E.1-14 E.1.4 References ................................................................................................................................ E.1-15 LIST OF TABLES Table E.1-1. Geologic Time Scale......................................................................................................... E.1-2 Table E.1-2. Geology of the High Plains ............................................................................................. E.1-3 Table E.1-3. Fossils Potentially Found in Study Area Geologic Formations ................................ E.1-10 LIST OF FIGURES Figure E.1-1. Surface Geology.............................................................................................................. E.1-5 Figure E.1-2. Bedrock Geology ............................................................................................................. E.1-6 ATTACHMENTS Attachment A. Abbreviations and Acronyms Attachment B. Bedrock Geology January 2013 Nebraska’s Keystone XL Pipeline Evaluation i Appendix E.1 | Geology Technical Memorandum Final Evaluation Report APPENDIX E.1 GEOLOGY TECHNICAL MEMORANDUM This technical memorandum describes existing geological, mineralogical, and paleontological Based on evaluation of potential seismic conditions along the proposed Nebraska Reroute; hazards along the proposed Nebraska potential impacts from construction, operation, and Reroute, the risk of potential impact to the pipeline from earthquake ground motion maintenance of the Keystone XL Pipeline; and general would be considered minimal. The mitigation measures to avoid or reduce potential proposed Nebraska Reroute would not cross impacts. any known active faults and would be The general geologic conditions discussed in this located outside of known zones of high seismic hazard. technical memorandum are associated with topography, development of soils, and the location and availability of groundwater. E.1.1 EXISTING CONDITIONS The designated Study Area for reviewing impacts on geology for the proposed Nebraska Reroute consists of a 110-foot-wide temporary easement centered on the route that would extend from the Nebraska state line in Keya Paha County to York County, Nebraska. E.1.1.1 Landscape The proposed Nebraska Reroute would pass through the eastern third of Nebraska. Nebraska is located in the High Plains portion of the Great Plains physiographic province. The High Plains extend from southern South Dakota to northwestern Texas. The landscape of this region is described as a large, eastwardly tilted surface formed by weathered material deposited from erosion of the early Rocky Mountains, beginning about 65 million years ago. Gently sloping, smooth plains characterize the High Plains (U.S. Department of State [DOS], 2011; Gutentag et al., 1984). Elevations along the proposed Nebraska Reroute range from about 2,200 feet above mean sea level in the north to 1,750 feet above mean sea level near the south. E.1.1.2 Geologic History of High Plains Geologic history is measured on the geologic time scale. The geologic time scale comprises standard stratigraphic divisions based on rock sequences and is calibrated in millions of years (see Table E.1-1) (U.S. Department of the Interior, U.S. Geological Survey [USGS] Geologic Names Committee, 2007). The geologic history of the High Plains focuses on the structural and depositional history of the east-central Rocky Mountains and adjacent plains, from the Late Cretaceous (about 65.5 million years ago) to the present. The Laramide Orogeny, or period of mountain building, began about 65.5 million years ago at about the same time as the great interior sea retreated (Gutentag et al., 1984). Mountain formation continued into Tertiary time. The Tertiary Period (65.5 to 2.6 million years ago) began with a long period of no recorded placement of material in most of the High Plains. The oldest Tertiary rocks found on the High Plains are of Oligocene age (33.9 to 23.0 million years ago). During the Tertiary Oligocene January 2013 Nebraska’s Keystone XL Pipeline Evaluation E.1-1 Final Evaluation Report Appendix E.1 | Geology Technical Memorandum Epoch, volcanism was widespread in the mountains and enormous quantities of volcanic debris and sediment eroded from the mountain were deposited on the plains. During the Tertiary Miocene Epoch (23.0 to 5.3 million years ago), sedimentation on the plains continued with some volcanic material deposited as well as weathered debris from the mountains. Most of the sediments making up the High Plains Aquifer were deposited during this time. The Tertiary Pliocene Epoch (5.3 to 2.6 million years ago) was a period of continued uplift and erosion of the mountains. Table E.1-1. Geologic Time Scale Era Period Epoch Million Years Ago Recent 0.01 to present Quaternary Pleistocene 2.6 to 0.01 Pliocene 5.3 to 2.6 Miocene 23.0 to 5.3 Cenozoic Cenozoic Tertiary Oligocene 33.9 to 23.0 Eocene 55.8 to 33.9 Paleocene 65.5 to 55.8 Cretaceous 145.5 to 65.5 Jurassic 199.6 to 145.5 Mesozoic Mesozoic Triassic 251.0 to 199.6 Permian 299.0 to 251.0 Pennsylvanian 318.0 to 299.0 Mississippian 359.0 to 318.0 Devonian 416.0 to 359.0 Paleozoic Paleozoic Silurian 444.0 to 416.0 Ordovician 488.0 to 444.0 Cambrian 542.0 to 488.0 Source: Korus and Joeckel, 2011 The sculpting of the High Plains continued through the Quaternary Period (2.6 million years ago to present). Large quantities of sediment were eroded from the mountains and the plains. Giant braided streams (streams flowing in several channels that divide and reunite) transported large quantities of silt, sand, and gravel and deposited these sediments in stream valleys and terraces. Winds blew sand and silt from the stream valleys and deposited them as dune sand and loess over large parts of the High Plains (Gutentag et al., 1984). E.1-2 Nebraska’s Keystone XL Pipeline Evaluation January 2013 Appendix E.1 | Geology Technical Memorandum Final Evaluation Report E.1.1.3 Geology of Nebraska The surface of Nebraska is almost entirely covered by sand and gravel, silt, and clay of Quaternary age (see Table E.1-1 and Figure E.1-1). The rocks underlying the surface material are sedimentary rocks of Cretaceous and Tertiary age (see Table E.1-2 and Figure E.1-2). Surface Geology of Nebraska Reroute Sands and gravels and silts of Quaternary age characterize the general surface geology of Nebraska. Major surface deposits along the proposed Nebraska Reroute include alluvium (deposited by stream or body of moving water), loess (windblown silts), eolian (windblown sands) and colluvium (deposited or built up at the bottom of a low-gradient slope) (USGS, 2012a). The central and southern sections of the proposed Nebraska Reroute are largely overlain by loess. Sandy soils are found along the northern portion of the route. A relatively sharp line separates the boundary between the sandy soils and loess (see Figure E.1-1). Table E.1-2. Geology of the High Plains Glacial Period Epoch Formations Lithology Era Stage Surface Geology Fine-to-medium-sized sands with Sand Hills dune sands small amounts of clay, silt, and Holocene coarse sand Fine silt with lesser