Information Circular 41 Geology of the Pea Ridge
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INFORMATION CIRCULAR 41 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY BEKKI WHITE, DIRECTOR AND STATE GEOLOGIST INFORMATION CIRCULAR 41 GEOLOGY OF THE PEA RIDGE AND GARFIELD QUADRANGLES, BENTON COUNTY, ARKANSAS by Angela Chandler and Scott Ausbrooks Little Rock, Arkansas 2010 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY BEKKI WHITE, DIRECTOR AND STATE GEOLOGIST INFORMATION CIRCULAR 41 GEOLOGY OF THE PEA RIDGE AND GARFIELD QUADRANGLES, BENTON COUNTY, ARKANSAS by Angela Chandler and Scott Ausbrooks Little Rock, Arkansas 2010 STATE OF ARKANSAS Mike Beebe, Governor Arkansas Geological Survey Bekki White, State Geologist and Director COMMISSIONERS Dr. Richard Cohoon, Chairman…………………………Russellville William Willis, Vice Chairman…………………………...Hot Springs David J. Baumgardner…………………………………...Little Rock Brad DeVazier…………………………………………….Forrest City Keith DuPriest……………………………………………..Magnolia Quin Baber………………………………………………...Benton David Lumbert……………………………………………..Little Rock Little Rock, Arkansas 2010 Table of Contents Introduction……………………………………………………….1 Stratigraphy………………………………………………………..2 Structure…………………………………………………………..13 Lineaments……………………………………………………….14 Faults………………………………………………………………..15 Karst………………………………………………………………….18 Economic Geology……………………………………………..20 Acknowledgments……………………………………………..21 References…………………………………………………………22 Geology of the Pea Ridge and Garfield Quadrangles, Benton County, Arkansas Angela Chandler and Scott Ausbrooks 2009 Introduction This report is one in a series of companion within the area with a population of less than reports to Digital Geological Quadrangle Maps 500 include Avoca, Garfield and Gateway. One published by the Arkansas Geological Survey. small town (Lost Bridge Village) is located on Its purpose is to: 1) provide a more detailed Beaver Lake. Pea Ridge National Military Park is discussion of the stratigraphy in the located on the Pea Ridge quadrangle and quadrangles, 2) provide surface and subsurface encompasses approximately seven square geologic interpretations and 3) provide miles. Portions of Beaver Lake including Indian information pertaining to economic natural Creek Public Use Area and Lost Bridge Public resources in the area. Use Area are present on the Garfield quadrangle. The area is easily accessed by state The Pea Ridge and Garfield quadrangles are and county road systems. A section of the located northeast of Rogers, Arkansas in the Burlington Northern and Sante Fe Railway northwestern part of the state, Missouri being system extends from north of Gateway on the the northern border (Fig. 1). The area is rural Garfield quadrangle southwest to the Pea Ridge with the largest town being Pea Ridge with a quadrangle following Highway 62 to the Rogers population of 2,346. Smaller communities Municipal Airport. Figure 1. Location map of Pea Ridge and Garfield Quadrangles. 1 The Pea Ridge and Garfield Quadrangles are historic descriptions of the prairies and located in the Ozark Plateaus Region of north economic geology of the area. A good Arkansas. Specifically, the majority of the stratigraphic synthesis had yet to be developed. quadrangles are located on the Springfield The Pea Ridge quadrangle was mapped in the Plateau surface, consisting mostly of a fairly flat Fayetteville Folio by Adams and Ulrich in 1905. or gently rolling topography which is capped by This folio contains detailed descriptions of the Mississippian Boone Limestone. The formations but covers such a large area that a escarpment between the Springfield and Salem comprehensive geologic map of Pea Ridge is Plateaus is present on the Garfield Quadrangle lacking. near Beaver Lake. In this area tributaries to the lake have dissected the plateau surface creating Geologic worksheets for both quadrangles were fairly steep hollows that expose older Devonian developed for the Geologic Map of Arkansas, and Ordovician formations. Several hills of 1976. The Pea Ridge geology for the Geologic small areal extent rise above the Springfield Map of Arkansas, 1976, was based loosely upon Plateau surface and are capped by the work done in the Fayetteville Folio. The Mississippian Wedington Sandstone Member of Garfield Geologic Worksheet produced by E.E. the Fayetteville Shale. Glick in 1970 was based on work by Purdue and Miser, (1916). Previous research in this area is limited to a couple of publications in the late 1800’s and early 1900’s. Simonds and Hopkins (1894) discuss the geology of Benton County with Stratigraphy Approximately 400 to 700 feet (121‐213 m) of drainages and a hilly topography. These steep Lower Ordovician, Middle to Upper Devonian, drainages also form the escarpment between Lower and Upper Mississippian and Quaternary the Springfield and the Salem Plateau surfaces. age strata are present on these quadrangles Upper Ordovician and Devonian strata crop out (Fig. 2). The Lower Mississippian Boone around Beaver Lake and its tributaries on the Limestone comprises the surface rock over the Garfield quadrangle and form the surface of the majority of the quadrangles and forms the Salem Plateau. Upper Mississippian age strata surface of the Springfield Plateau. The are present on the higher hills that are capped Springfield Plateau surface is fairly flat on the by resistant sandstone of the Wedington Pea Ridge quadrangle, however on the Garfield Member of the Fayetteville Shale. Quaternary quadrangle near Beaver Lake the plateau terrace and alluvium deposits are present surface is heavily dissected creating steep within the larger creek drainages in the area. 2 3 Lower Ordovician Cotter Dolomite The Cotter Dolomite was named by E.O. Ulrich fragments or nodules, especially near the upper for the town of Cotter, Arkansas where it is well contact with the Powell Dolomite. exposed (Purdue and Miser, 1916). A type Stromatolites, oolitic chert and drusy quartz section at the Cotter Bridge was designated by fragments are present in the dolostone in this Cullison in 1944. The Cotter ranges up to 400 area. Stromatolites are present as small crinkle feet (121 m) in thickness, however only the bands or as large heads up to 3 feet (.9 m) in upper 60‐100 feet (18‐30 m) of this formation is diameter. Large stromatolites create an exposed on the Garfield Quadrangle. undulatory surface that gives the appearance of Dolostones in this unit are exposed along disturbed strata. At a few localities greenish Beaver Lake and in tributaries to the lake. The clay shale and white coarse‐grained sandstone Cotter Dolomite is overlain unconformably by are present in the upper portion of the unit. the Powell Dolomite or the Clifty Sandstone in The base of the sandstone is not a planar bed. the Garfield quadrangle. Instead it fills in lows and drapes over the irregular dolostone surface. Small vugs This formation consists of fine‐to medium‐ containing pink dolomite are present in the grained gray dolostone that is thin‐ to thick‐ dolostone in the Indian Creek area. bedded. The dolostone usually contains chert (A) (B) Figure 3. (A) Chert fragments in the Cotter Dolomite. (B) Weathered stromatolitic surface in the Cotter Dolomite. Stromatolites are 2‐3 inches across. Lower Ordovician Powell Dolomite The Powell Dolomite was named by E.O. Ulrich up to 300 feet (91 m) thick. Where present, this for Powell Station, Arkansas where it is well unit ranges up to 30 feet (9 m) thick around exposed on the White River branch of the St. Beaver Lake and its tributaries on the Garfield Louis, Iron Mountain & Southern Railway quadrangle. Middle and Upper Ordovician, (Purdue and Miser, 1916). The Powell ranges Silurian and Lower Devonian formations are not 4 present at the surface in this area so that the near the upper part of the unit. The Powell also Powell is unconformably overlain by the Middle contains laminated flat crinkle stromatolites. At Devonian Clifty Sandstone. a few localities, very thin bedded gray‐green to reddish shales are interbedded with the This formation consists of very fine‐ to fine‐ dolostone. Sandstone is present in the upper grained gray to white dolostone that is very portion of the Powell in paleokarst features. thin‐ to medium‐bedded. The very thin‐ to thin‐ The basal contact with the Cotter Dolomite is bedded dolostone is argillaceous and weathers placed at the appearance of banded chert to small blocky pieces. Calcite nodules are and/or chert nodules or breccia. The Powell present near the contact with the overlying Dolomite is relatively chert free which along Clifty Sandstone. Gastropods are present in a with the argillaceous fine‐ grained character thin bed of mottled dolostone at one locality helps to distinguish it from the Cotter Dolomite. (A) (B) Figure 4. (A) Weathered Powell Dolomite. (B) Interbedded shale in the Powell Dolomite. Middle Devonian Clifty Limestone The Clifty was originally named the Clifty the Clifty as primarily a sandstone unit that Limestone for exposures in the East Fork of appears to be confined to the area surrounding Little Clifty Creek, Arkansas where it consists of Beaver Lake, Benton and Carroll Counties, a 2 ½ foot (0.7 m) bed of sandy limestone Arkansas. The Clifty is subsequently referred to (Purdue and Miser, 1916). In 1967 Wise and as the Clifty Sandstone by workers in Arkansas Caplan state that the Clifty Limestone is actually and for purposes of this publication. The Clifty a lens in a sandstone unit that is approximately Sandstone ranges from 2‐10 feet (0.6‐3 m) on 20 feet (6 m) thick and unconformable with the the Garfield quadrangle. overlying and underlying formations. Subsequent stratigraphic