Ogallala formation

the Ogallala Formation of Miocene age and overlying hydraulically connected Quaternary deposits, if present. Northwestern Nebraska, south central South Dakota, and southeastern Wyoming: the fractured upper part of the Brule Formation or the Arikaree Group.

The Ogallala Formation is the primary source of potable and irrigation waters in the Great Plains and drives much of the region's economy. Measured water-level declines of >200 feet from predevelopment levels are common in southwestern Kansas (McGuire, 2009; Fig. 2) where the usable lifetime of the aquifer at present rates of withdrawal ranges ...Ogallala Formation Using Shallow Holes. In Proceedings of the Ogallala Aquifer Symposium, April 30 and May 1, 1970, Texas Tech University, Lubbock, Texas. · Dvoracek, M. J. and s. H. Peterson. 1970. Development of Systems for Ground Water Recharge into the Ogallala Formation. In Water Resources Institute 1970 Annual Report.The Miocene-age Ogallala Formation is composed of Rocky Mountain-derived fluvial sediments that progressively filled preexisting valleys and ultimately mantled the uplands. The three regionally recognized members cannot be easily differentiated in Phillips County. However, the carbonate-cemented mortar beds are conspicuous throughout the county ...rocks, are called the Ogallala Group (formerly the Ogallala Formation) because the rocks are now subdivided into two or more formations (the defi-nition of a group). A number of anom-alously thick, large-grained volcanic ash beds are also found in the Ogallala Group. 6. A few of these ash beds con-tain large vertebrate fossils. 1. Oard, M.J., 2008.Morghan Mohan March 2, 2021 INTRO TO ENVIRONMENTAL SCI I (ENVR1401) Ogallala Aquifer Quiz _ D ___10. As a proactive step for future water preservation in the Ogallala formation in Texas, one solution the article mentions that could be beneficial would be (A) reducing water subsidies to farmers on public lands (B) letting the groundwater conservation districts have a bigger say in shared water ...

However, its crown jewel is the Scotts Bluff National Monument, an 800-foot-high natural rock formation offering stunning North Platte River vistas, immersive country, and cityscapes, including the equally iconic Chimney Rock. ... Ogallala View of Front Street in Ogallala, Nebraska, via YULIYAPHOTO / Shutterstock.com.Geology of Texas. Texas contains a wide variety of geologic settings. The state's stratigraphy has been largely influenced by marine transgressive-regressive cycles during the Phanerozoic, with a lesser but still significant contribution from late Cenozoic tectonic activity, as well as the remnants of a Paleozoic mountain range.The Ogallala Formation consists mostly of coarse sedimentary rocks in its deeper sections, which transition upward into finer-grained material. The water-saturated thickness of the Ogallala Formation ranges from a few feet to more than 1,000 feet. Its deepest part is 1200 ft. (300 m) and is generally greater in the Northern Plains. [10]The Ogallala Formation was named by Darton (1899) from a locality in southwestern Nebraska that he later (1920) referred to as Ogallala Station. Elias (1931, 1932, 1935, 1942) made detailed studies of the Ogallala in western Kansas and described fossil endocarps, nutlets, and anthoecia from the formation while Lugn (1938, 1939) studied the ...The Ogallala Formation of Tertiary (Pliocene) age is the principal aquifer in the Southern High Plains of western Texas and eastern New Mexico. This heavily pumped aquifer supplies practically all the water used for irrigation, municipal, industrial (except oil-field repressuring), and domestic purposes. Although the ground water in the Ogallala Formation in the Southern High Plains is common ...The upper Tertiary Ogallala Formation contains the Ogallala (High Plains) aquifer, which is the major source of water for agricultural and domestic use on the Southern High Plains of Texas and New Mexico. Locally, perched aquifers overlie the Ogallala aquifer. This study, based on outcrop and subsurface data, provides a regional stratigraphic ...

Ogallala: Formation: Valentine: Member: Cornell Dam: Age: 16.0 - 13.6 Ma Miocene: Interval: Barstovian: Lithology: sandstone: Number of Collections: 9: Number of Occurrences: 308: ... Chantell C. J. (1963) Urodele remains from the Valentine Formation of Nebraska, Copeia 1963 3, 505-510: Chantell C. J. (1964) Some Mio-Pliocene hylids from the ...Quartzite has been reported from the Ogallala formation in Franklin County, Nebraska, just north of the Kansas line, and from the Missouri Valley area in northeastern Nebraska and southeastern South Dakota. Samples were also obtained from two localities in Texas, one 13 miles northeast of Midland and one 3 miles south-southwest of Canyon. ...Writing a letter is an important skill to have, whether it be for business or personal reasons. Knowing the basics of letter writing format can help you create a professional and effective letter.Symposium papers describe elements of the stratigraphy, biostratigraphy, hydrology, and geomorphology of the Ogallala and Blackwater Draw Formations. CONTENTS Introduction Acknowledgments Depositional facies of the Miocene-Pliocene Ogallala Formation, northwestern Texas and eastern New Mexico, by T. C. Gustavson and D. A. WinklerFrye (1945a) presented an hypothesis of "Algal limestone" formation in lakes that occupied consequent depressions and abandoned channel segments, after deposition had virtually ceased on the piedmont plain of alluviation that marked the top of the Ogallala deposits. Plate 2--Ogallala formation in west-central Kansas. A.Of these, the Ogallala aquifer underlies most of western Kansas and consists mainly of the Ogallala Formation, a geologic unit that formed from sediment eroded off the uplifting Rocky Mountains. The southwest Kansas portion of the Ogallala has suffered the greatest losses since groundwater levels started dropping in the 1950s. In the drought ...

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The northern boundary of the Raton section is placed somewhat indefinitely at the northern limit of the area injected by igneous dikes. The eastern boundary of the Raton section is at the eastern margin of the lavas of Mesa de Maya and adjoining mesas, where lava-capped outliers of Ogallala Formation are separated from the Ogallala of the High Plains only by the canyon of Carrizo Creek.May 21, 2020 · The aquifer is a structural subset of the Ogallala formation, which is a geological structure that formed through the Miocene and Pliocene eras (i.e., 23 Mya to 2 Mya) (Kansas Geological Survey, 2015). The composition of the aquifer is a mixture between “silt, sand, gravel, and clay—rock debris” (Kansas Geological Survey, 2019) that ... The Ogallala formation of Pliocene age is the principal aquifer in the Southern High Plains of Texas; it supplies practically all the water used for all purposes. The formation is continuous throughout most of the Texas part of the Southern High Plains and extends into New Mexico. The .formation consists chiefly ofRice Formation. Paleozoic Era. Cambrian System. Upper Cambrian Series. Lamotte Sandstone. Bonneterre Dolomite. Undifferentiated Upper Cambrian and Lower Ordovician. ... Ogallala Formation. Quaternary System. Pleistocene Series. Northeastern Area--Nebraskan Stage. David City Formation. Iowa Point Till. Northeastern Area--Attonian Stage.

Ogallala Formation all probably experienced unique histories. Consequently, little logical support exists for an expectation of regional lithostratigraphic continuity along the north-south extent of the Ogallala Formation. Moore et al. (1944) and Frye et al. (1956) adopted member names of the Ogallala Formation in Kansas that wereThe Ogallala Formation is a Miocene to early Pliocene geologic formation in the central High Plains of the western United States and the location of the Ogallala Aquifer. In Nebraska and South Dakota it is also classified as the Ogallala Group.Ogallala Aquifer, Texas By R. F. Brown andW. S. Keys Abstract Four recharge tests were conducted by injecting water from playa lakes through wells into the Ogallala Formation. Injection was by gravity flow and by pumping under pressure. At one site, 34-acre feet of water wasThis aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to …Of these, the Ogallala aquifer underlies most of western Kansas and consists mainly of the Ogallala Formation, a geologic unit that formed from sediment eroded off the uplifting Rocky Mountains. The southwest Kansas portion of the Ogallala has suffered the greatest losses since groundwater levels started dropping in the 1950s. In the drought ...The member names for the Ogallala Formation (including the Valentine, Ash Hollow, and Kimball) in Kansas of Zeller (1968) are abandoned. The Ogallala Formation in Kansas includes strata of Miocene and earliest Pliocene age, revising earlierThe Ogallala formation consists of fluviatile, late Tertiary (Neogene) deposits that underlie the surface that forms the High Plains. Ranging up to 300 feet in thickness, these deposits extend from Texas to South Dakota in a broad belt several hundred miles wide. Contrary to prevalent concepts, the Ogallala was not deposited as a series of ...is the Ogallala Formation of Tertiary age. The Ogallala Formation is composed of sediments eroded from the ancestral Rocky Mountains by streams and wind. The dominant mode of deposition was by braided streams that coalesced to form broad alluvial fans (Gutentag and others, 1984). The Ogallala Formation consists of semi-consolidated layers ofBetween 1950 and 2013, the water levels dropped over 250 feet in an Ogallala well near Lubbock, Texas. The aquifer has seen more moderate declines elsewhere, but it's causing problems for cities, well owners and irrigators alike. Oklahoma only permits its irrigators enough groundwater to cover each acre of their land with 2 feet of water per ...The occasional detection of pesticides in deeper parts of the Ogallala Formation indicates that contamination pathways exist. Dissolved solids, which are a direct measure of salinity, had 29 ...In Brief. If spread across the U.S. the aquifer would cover all 50 states with 1.5 feet of water. If drained, it would take more than 6,000 years to refill naturally. More than 90 percent of the ...

Del sulfur-34 sulfate values range from a high of +6.9 parts per thousand to a low of -25.1 parts per thousand. Sulfate increases from about 20 milligrams per liter to more than 350 milligrams per liter from west to east. Increasing concentration of dissolved solids, lighter Del sulfur-34 values, and increasing sulfate concentration in the east ...

The Ogallala Formation is the principal geologic unit in the High Plains aquifer in eastern Colorado and New Mexico. The Ogallala generally consists of an unconsolidated and poorly sorted sequence of gravel, sand, silt, and clay. Moderately to well-cemented zones within the Ogallala are resistant to weathering and form ledges in outcrop areas. The Ogallala Formation of late Miocene to early Pliocene age consists of heterogeneous sequen-ces of coarse-grained sand and gravel in the lower part, grading upward into clay, silt, and fine sand. In Texas, the Panhandle is the most extensive region irrigated with groundwater. In 2008, almost 96 percent of the water pumped from the Ogallala ...Answered by sarahchrisssy. 1. Of the eight states that have land in the Ogallala Aquifer territory, the one state with the largest percentage of Ogallala density would be. (D) Nebraska. 2. The one state that has a different water law - "The Rule of Capture" that further exacerbates the drawdown of water from the Ogallala is. (A) Texas.Flaxville Gravel and Ogallala Formation Arikaree Formation White River Group Wasatch and Golden Valley Formations: Ogallala Formation Arikaree Formation White River Group: Mostly missing because of erosion or nondeposition: Oligocene: 37-38: Eocene: 53-54: Paleocene: 65: Fort Union Formation:Ogallala Formation; but in the lower Pecos Valley area (Roswell, NM to Pecos, TX), correlative depression and valley fills have been mapped variously as "older alluvium, quartzose conglomerate, valley-fill alluvial deposits," and as the Gatuňa Formation. Gatuňa-Ogallala chronologic and nomenclature problems have not Ogallala Group or Formation (Miocene) at surface, covers < 0.1 % of this area. Silt, sand, sandstone, gravel and conglomerate. Predominantly interfingered fine- to coarse grained, poorly sorted, arkosic, fluvial deposits of light-gray, light-olive-gray, and grayish-green calcareous silt and sand, and locally poorly consolidated conglomerate ...Expert Answer. Answer:- The elevation of the South Pla …. Previous 14 UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS COLORADO PIEDMONT (South Platte Drainage) + HIGH PLAINS Pleistocene a Recent 6020 feet Cedar Point (near Limon) Ogallala Earliest Piocene fm. E е V a t i o Pawnee Ck. fm Miocene n White River fm. Oligocene White R. fm ...outcrops of the Ogallala Formation, which is an important underground aquifer throughout the High Plains. Here at Scott Lake, the Ogallala crops out at the surface as hard, dense sandstones cemented with calcium carbonate, known locally as mortar beds. At the south end of the park, the Ogallala forms a long ridge called Devil's Backbone.

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Ogallala Group or Formation (Miocene) at surface, covers < 0.1 % of this area. Silt, sand, sandstone, gravel and conglomerate. Predominantly interfingered fine- to coarse grained, poorly sorted, arkosic, fluvial deposits of light-gray, light-olive-gray, and grayish-green calcareous silt and sand, and locally poorly consolidated conglomerate ...The Neogene Ogallala Formation consists of discontinuous beds of conglomerate, sandstone, and siltstone composed of sediment eroded from the Rocky Mountains and deposited as a broad, eastward ...The Ogallala formation unconformably overlies Permian, Triassic, Jurassic and Cretaceous strata and consists primarily of heterogeneous sequences of coarse-grained sand and gravel in the lower part grading upward into fine clay, silt, and sand. Gravel commonly occurs in layers in the basal section and ranges in size from boulders to pea size.The upper Tertiary Ogallala Formation contains the Ogallala (High Plains) aquifer, which is the major source of water for agricultural and domestic use on the Southern High Plains of Texas and New Mexico. Locally, perched aquifers overlie the Ogallala aquifer.sediments and paleosols of the Ogallala Formation. During the trip, we will visit sites and landscapes that have a long and rich history of geologic investigation. In addi-tion to previously published results, we also present new data on the sedimentology, geochronology, paleontology, and paleoichnology of Cenozoic High Plains deposits.Photomicrograph of transverse section of large (3 cm diameter) rhizolith from Miocene Ogallala Formation (Fig. 1, loc. 7; south side of Highway 34, east of Wray, CO). Note dotted micrite and transverse, longitudinal, and oblique sec- tions of small rhizoliths with epidermal cell structure preserved by opal (arrow). Plane light. be compared ...base of the Ogallala Formation to the potentiometric surface. The saturated thickness in Oklahoma ranges from more than 400 feet to less than 50 feet. Natural recharge to the aquifer from precipitation occurs throughout the area but is extremely variable. Dryland agricultural practices appear to enhanceOct 11, 2018 · The Ogallala Formation ranges in thickness from a few meters to more than 90 m. The formation was deposited on an erosional surface exposing rocks of Cretaceous age and was itself eroded after deposition, partially accounting for the changes in thickness. BEG Primary. About. Who We Are; Contact; Media Contact; Job Opportunities; Annual Reports and Information; Bureau Directions and Maps; Area Hotels; Strategic PlanThere's plenty to do in Ogallala, Nebraska – so don't miss out on the fun! 525 Main St, Worcester, MA 01608. Mon – Sat: 9:00am–18:00pm. Sunday CLOSED. 508-653-3352. North America. United States; ... Located in the scenic high plains of western Nebraska, this natural rock formation has been a source of wonder and inspiration for centuries.Summary. The Edwards-Trinity (High Plains) Aquifer is a minor aquifer that underlies about 9,000 square miles of the Ogallala Aquifer in western Texas and eastern New Mexico. Its water-producing units include sandstone of the Antlers Formation (Trinity Group) and limestone of the overlying Comanche Peak and Edwards formations.The Ogallala Formation in Kansas includes strata of Miocene and earliest Pliocene age, revising earlier correlation to the Pliocene only (Zeller, 1968). The Kansas Geological Survey is abandoning use of the term "Tertiary," to be replaced by the term "Neogene." International stage boundaries for the Neogene have not been established in Kansas. ….

Preliminary Magnetostratigraphic Analyses of the Neogene Ogallala Formation in southwestern Kansas and northeastern New Mexico for the High Plains-Ogallala Drilling Program. Geological Society of America, Rocky Mountain Section - 64th Annual Meeting. 33.Four-year project delivers science-based solutions for managing Ogallala Aquifer. By Anne Manning. Published July 6, 2020. Stretching 174,000 square miles across the High Plains, bringing life to fields of corn, cotton and wheat, lies the vast geologic resource known as the Ogallala Aquifer. The largest freshwater aquifer in the world, the ...The Ogallala aquifer, which underlies the Southern High Plains, consists of the saturated sediments of the Neogene Ogallala Formation. The aquifer is the main source of water for the High Plains of Texas and New Mexico and is being severely depleted by extensive pumpage for irrigation.base of the Ogallala Formation to the potentiometric surface. The saturated thickness in Oklahoma ranges from more than 400 feet to less than 50 feet. Natural recharge to the aquifer from precipitation occurs throughout the area but is extremely variable. Dryland agricultural practices appear to enhanceOgallala formation reveal that, in 1968, water withdrawn as groundwater from the Ogallala was almost twice as much as the total water usage from all the surface storage in the area. Most of the present withdrawals is for irrigation purposes; about 22% is for municipal and industrial use, and a small percentage is used in water-flooding of oilOgallalaFormation,Texas BureauofEconomicGeology TheUniversityofTexasatAustin Austin,Texas 78712 W.L.Fisher,Director 1980 by StevenJ.Seni Preparedforthe U.S.DepartmentofEnergy underContractNumber DE-AC97-80ET-466153. What was the elevation of the South Platte River on Figure 4 at the time the Ogallala Formation was deposited? Explain your reasoning. To answer this question, consider your answers to the questions above. (2) 4. Calculate the rate at which the South Platte River has eroded Colorado's Great Plains between Cheyenne and Cedar Point. Express your answer in feet/million years.The Ogallala Formation of Miocene/Pliocene age is present over a large area of the Great Plains in the central US. The formation is composed of mostly clastic material eroded and transported eastward from the Rocky Mountains by eastward flowing rivers and streams. It contains the life-giving water that supports the population and farming activities of this vast area. However, this precious ...Ash Hollow member of Ogallala formation. Includes volcanic ash beds Dellvale, Fort Wallce, Rawlins (used to correlate with type), and Reamsville. Average thickness about 75 to 200 feet; is 305+ feet at type (Ash Hollow, southeast of Lewellen, NE). In northern Kansas, underlies Kimball member of Ogallala, and overlies Valentine member of ... Ogallala formation, The Ogallala Formation of late Miocene to early Pliocene age consists of heterogeneous sequen-ces of coarse-grained sand and gravel in the lower part, grading upward into clay, silt, and fine sand. In Texas, the Panhandle is the most extensive region irrigated with groundwater. In 2008, almost 96 percent of the water pumped from the Ogallala ..., Oklahoma The Ogallala aquifer is one of the major aquifers in Oklahoma, underlying the Panhandle and parts of the northwest regions. In the eastern part of the Oklahoma Panhandle, the Ogallala formation often sits directly on top of consolidated sediments, which are more than 250 million years old., The Ogallala Formation is Neogene in age; Paleogene rocks do not occur in Kansas. This paper outlines Neogene ("Tertiary") nomenclature changes to Zeller (1968) that are now formally adopted by the Kansas Geological Survey (KGS). Lithostratigraphy of the Ogallala Formation, When it comes to job searching, having a great resume is key. A resume is your first impression to potential employers, and it’s important to make sure that you’re presenting yourself in the best possible light. One way to ensure that your ..., A. GENERAL GEOLOGY, STRATIGRAPHY, AND HYDROLOGY The Ogallala Formation in Texas is the southernmost extension of the major water-bearing unit underlying the physiographic province of North America. It was named by Darton (1898) for the town of Ogallala, Nebraska, near the type locality. Following the Laramide revolution in which the southern Rocky Mountains were uplifted…, To format a government or military situation report, known as a sitrep, follow a template that details what information goes on each line of the report. You need a computer with Internet access. Expect the process to take about an hour., The Oklahoma Panhandle and adjacent areas in Texas, Kansas, Colorado, and New Mexico have prospered because of the development of supplies of fresh water and of oil and gas. The Ogallala and, in places, Cretaceous rocks produce fresh water for irrigation, public supply, and domestic and stock use through approximately 9,000 irrigation and public supply wells and a large but undetermined number of, The Ogallala Formation is composed of pedogenically modified fluvial silts, sands, and gravels. Calcic paleosols occur with high stratigraphic frequency and are characterized by abundant carbonate ..., Much of the Ogallala Formation was eroded away and stream channels became established. Sketch courtesy of Wyoming Geological Survey. Today, the Laramie Range, a northern extension of the Colorado Front Range, extends from the Colorado—Wyoming state line north and west to near Casper, Wyoming. East of the mountains is a section of the Great ..., One outcrop of Ogallala chert was examined in the W2 sec. 7, T. 14 S., R. 38 W., Wallace County. At this locality the chert occurs high in the Ogallala and is not far below the "Algal limestone" which marks the top of the formation. The occurrence of such rock in the Tertiary of Wallace and Logan Counties was noted as early as 1874 by Mudge., Contrasting management impacts in the Northern and Southern Ogallala. For the Northern Ogallala, sufficient precipitation helps prevent the depletion of the aquifer caused by water withdrawals. Without assimilating GRACE observations, the model tends to underestimate groundwater recharge. So, assimilation is essential to capture water storage ..., The Ogallala Formation of late Tertiary age was described first by Darton in some detail from study of the unit in western Nebraska. Darton also identified Tertiary sediment and rock layers older than the Ogallala, called the Arikaree Formation, Gering Formation, and the still older Brule Clay in parts of western Nebraska. ..., Origin of the Ogallala. The Ogallala formation in Texas is the southernmost extension of the major water-bearing unit underlying the physiographic province of North America. It was named in 1898 by N.H. Darton for the town of Ogallala, Nebraska, near where the formation was discovered. , Abstract. The geologic and hydrogeologic characteristics of Tertiary lithostratigraphic units (Ogallala Formation and White River Group) that typically compose or underlie the High Plains aquifer system in southeastern Wyoming were described physically and chemically, and evaluated at a location on the Belvoir Ranch in Laramie County, Wyoming., Aug 4, 2011 · Frye (1945a) presented an hypothesis of "Algal limestone" formation in lakes that occupied consequent depressions and abandoned channel segments, after deposition had virtually ceased on the piedmont plain of alluviation that marked the top of the Ogallala deposits. Plate 2--Ogallala formation in west-central Kansas. A. , Ogallala formation often sits directly on top of consolidated sediments, which are more than 250 million years old. In Cimarron and western Texas counties, a younger formation of shale and sandstone called the Dockum group overlies the redbed. Other formations, including the Dakota Sandstone and Morrison Formation, also are found in the Oklahoma, Ogallala Formation (Miocene), western Kansas | South-Central Section of the Geological Society of America | GeoScienceWorld Books | GeoScienceWorld. All Books. By Publisher., The Ogallala Formation in Kansas includes strata of Miocene and earliest Pliocene age, revising earlier correlation to the Pliocene only (Zeller, 1968). The Kansas Geological Survey is abandoning use of the term "Tertiary," to be replaced by the term "Neogene." International stage boundaries for the Neogene have not been established in Kansas., Aquifers are underground layers of porous and permeable rock or unconsolidated sediment, such as sand and gravel, that hold water. Porous means that rocks contain pores, or holes, and permeable means the pores are interconnected in a way that allows water to flow from pore to pore. Spaces containing water in sand and gravel or loosely consolidated rock can be …, Ogallala Formation and saturated material of Quaternary Age in hydraulic connection with the Ogallala Formation. The High Plains aquifer is commonly referred to as the Ogallala aquifer. The High Plains aquifer is similar to a rigid sponge, partially saturated with water. The aquifer is composed of clay, silt, sand,, Ogallala High School is a secondary school located in Ogallala, Nebraska, United States. About. OHS is part of the Ogallala Public School District. The school takes in students …, The Ogallala Formation unconformably overlies Permian, Triassic, Jurassic, and Cretaceous strata and consists primarily of heterogeneous sequences of coarse-grained sand and gravel in the lower part grading upward into fine clay, silt, and sand. Water-bearing areas of the Ogallala Formation are, An aquifer is a geologic formation, a group of formations, or a part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.The areal and vertical location of major aquifers is fundamental to the determination of groundwater availability for the Nation. A principal aquifer is …, The Miocene-age Ogallala Formation is the principal member of the High Plains aquifer. It is the youngest Tertiary-age aquifer in the study area and consists of interbedded sandstone, gravel, silt, and clay. The Ogallala is the primary aquifer in …, Ogallala Formation is a calcareous grit or soft limestone containing a greater or less amount of interbedded and intermixed clay and sand, with pebbles of various kinds sprinkled through it locally, and a basal bed of conglomerate at many localities. In places it merges into a, Group or Formation Period Notes Ada Group/Ada Formation: Carboniferous: Altamont Formation: Carboniferous: Arbuckle Group/Arbuckle Formation: Ordovician: Arbuckle Group/Kindblade Formation: Ordovician: Atoka Formation, Base of Ogallala Formation: Top of Trinity Group : Top of Dockum Group : Base of Dockum Group : Comments: Points are locations where observations (such as surface and borehole geophysical data and drillers logs) were used to help develop hydrogeologic unit surfaces of the tops and bases of the gridded model., A Review of the Stratigraphy of the Ogallala Formation and Revision of Neogene ("Tertiary") Nomenclature in Kansas. Published online Dec. 17, 2009 as Current Research in Earth Sciences, Bulletin 256, part 2., The Ogallala is nearly horizontal, but tilts very gradually down to the east. The dashed line on Figure 1 links the High Plains near Cheyenne, Wyoming and Cedar Point, near Limon, Colorado, which are both at the same elevation. Figure 2 is a description of the Ogallala Formation (from the Sterling, Colorado 1x2° geologic map)., Ogallala Formation. Sand, silt, clay, gravel, and caliche. Sand, fine to cs-grain quartz, silty in part, caliche nodules locally, cemented locally by calcite and by silica, locally crossbedded. Minor silt and clay with caliche nodules, sandy in places. Gravel present locally, pebbles and cobbles of quartz, quartzite, minor chert, igneous rock ..., The Ogallala Formation is a wedge of sediments built up eastward of the Rocky Mountains as they were uplifted in the Miocene, ... The 20th century has witnessed a concerted effort to tap the more reliable Ogallala water sands. Predictably, the consequent high dependency on groundwater has removed more water than is naturally replaced, raising ..., The hydraulic gradient in the Ogallala Formation is approximately 12 feet per mile across the county. Aquifer tests indicate an average permeability of about 900 gpd per square foot. With an assumed porosity of 30 percent, the average velocity of the ground water is calculated to be v = (900 x 12) / (395 x 30) = 0.9 foot per day, or, The Ogallala Formation is widespread in the central and southern Great Plains, comprising the deposits at or near the surface in much of central-eastern New Mexico. The uppermost part of the formation generally consists of a zone containing a very high percentage of calcium carbonate, variously called "cap rock", "lime rock", and caliche. ...