Description of the Winslow Quadrangle

DESCRIPTION OF THE WINSLOW QUADRANGLE By A. H. Purdue. INTRODUCTION. The surface of most of that part of the plateau cut deep, canyon-like valleys from 500 to 1000 feet Below such escarpments there are benches^or grad which lies in Missouri is low and well rounded below the highest points. ually sloping surfaces, few of them exceeding a LOCATION AND AEEA. between the streams, but in the vicinity of White The streams south of the divide are swifter and quarter of a mile in width, and most of them much The Winslow quadrangle lies mainly in the west River, both in Missouri and Arkansas, the streams therefore cut faster than those north of it, with the narrower. In the northern and middle portions of ern part of Arkansas, north of Arkansas River. It have deep valleys with steep slopes, and the topog result that the valleys on the south are deeper and the area the escarpments in the main lie in hori is bounded by parallels 35° 30'and 36° and merid raphy is rugged. In Arkansas, just within the more precipitous. The slopes above the streams zontal planes, and the most prominent of them can ians 94° and 94° 30'. Its average width from east southern margin of the plateau, several outliers of are interrupted by numerous nearly perpendicular be followed for miles; but in the southern part they to west is about 28 miles and its length is about the Boston Mountains form conspicuous features escarpments produced by the differential weather slope southward with the dip of the rocks, so that 34^ miles. Its area is almost 969 square miles. of the landscape. ing of the alternating hard and soft beds of rock. any particular escarpment at length passes out of Nearly 29 square miles in the southwestern quarter Drainage. The direction of the drainage of the North of the divide these escarpments are practi sight beneath those above. of the quadrangle lie in Indian Territory. The area Ozark Plateau has been determined by the uplift cally horizontal, but south of it the dip of the rock The valleys extend northward, westward, and in Arkansas includes most of Crawford County, a of the region, and is therefore away from the axis, gives them a pronounced southward slope. southward from the main summits, the heads of small part of Franklin County, and the southern being in the main to the northwest and southeast. those from opposite slopes passing upward beyond half of Washington County except a narrow strip Most of the streams are small, only a few, such as TOPOGRAPHY OF THE QUADRANGLE. the former water divide, causing an interlocking or along the eastern side. Gasconade River on the northern slope and Cur RELIEF. interdigitation of the upper parts of the valleys GENERAL GEOGRAPHY OF THE OZARK REGION. rent and White rivers on the southern slope, being and making the present water divide very sinuous. of notable size. GENERAL FEATURES. The south slope of this division is much steeper LIMITS OF THE REGION. White River, the largest stream in the region, The Winslow quadrangle lies mainly in the west than the north slope. From the railroad tunnel at The Winslow quadrangle lies within the Ozark rises in the Boston Mountains and flows northward, ern portion of the Boston Mountains, extending Winslow southward to Chester, a distance of about region, known in geologic literature as the Ozark parallel to that portion of the divide which extends across them in a north-south direction. A small 8 miles, the fall is 910 feet, From the same level uplift. This physiographic region extends from from Springfield to Fayetteville, turns eastward for area near the northern border, about Prairie Grove, to Greenland, on the north slope, a distance of the lowlands bordering Missouri Kiver southward a short distance in the southern part of Missouri, and a still smaller one in the northwest corner, about 14 miles, the fall is only 400 feet. As above to the Arkansas Valley, and from Neosho or Grand then flows southwestward, in conformity with the about Summers, belong to the southward extension stated, the valleys of the south slope are much River, in Indian Territory, eastward to the Tertiary general slope of the plateau, to the lowlands of of the Ozark Plateau. These areas are level plains deeper than those of the north slope, as a result of lowlands of southeastern Missouri and eastern Arkansas, and thence into Arkansas River near its that stand about 1200 feet above sea level. A small the greater declivity and consequent greater cutting Arkansas, its area comprising 40,000 square miles. mouth. In Arkansas it receives Kings River from area in the southeast corner belongs to the Arkan power of the streams. In outline the region is roughly an ellipse whose the south, Buffalo River from the west, and North sas Valley region. The remainder about nine- major axis extends from the St. Francis Mountains Fork of White River from the north. tenths of the quadrangle lies within the greatly THE SOUTHERN AREA. of Missouri southwestward to the town of Wagoner, The course of White River is marked by numer dissected plateau that constitutes the Boston Moun General description. The northern area passes in Indian Territory, a distance of about 300 miles. ous bold and graceful swings, giving it the appear tains, and for the purpose of description may be imperceptibly into the southern area, but there is a On the south the Ozark uplift is bounded by the ance on the map of a meandering stream with a divided into a northern area and a southern area. marked difference between the topography of the Arkansas Valley, a synclinal trough extending east wide flood plain. In fact its valley is narrow, with two. The southern area slopes gradually south THE NORTHERN AREA. and west, which has been reduced by erosion to a steep sides. Alluvial deposits occur only here and ward and for the most part has an even surface. plain about 30 miles wide having an average eleva there, forming narrow strips along the stream. The General description. The northern area, extends It is well developed between the railroad and the tion of about 500 feet above sea level. Upon this slopes of the valley on the inside of the curves are from the northern part of the quadrangle south eastern border of the quadrangle, where the uni plain stand Sugarloaf Mountains, Magazine Moun long and gradual enough to permit travel over ward to about the latitude of Mountainburg, on formity of its surface is disturbed only by Winn tain, Mount Nebo, Carrion Crow Mountain, Petit them, but at the outer sides of the curves there are the St. Louis and San Francisco Railroad. The Mountain, the shallow valleys of the southward- Jean Mountain, and other elevations of less prom precipitous bluffs. It is evident from this that the numerous canyon-like valleys that so completely flowing streams, and a series of low, poorly defined inence, besides numerous low, parallel, east-west curves havej at least in part, been produced by lat dissect the region, as well as the highest points east-west ridges along the southern border. The ridges. The highest point is the summit of Maga eral shifting of the stream while it was cutting its of the quadrangle, occur in this division. Like even surface is not so common over the area west zine Mountain, which stands 2800 feet above sea bed downward. the remainder of the region, it is deeply cut into of the railroad, which is dissected by deeper val level. by streams that form steep-sided, narrow, canyon- leys, but it is well developed in the flat-topped THE BOSTON MOLnSTTAIlSrS. like valleys, leaving promiscuously distributed over divides between the streams, from Pine Mountain DIVISIONS OF THE REGION. Location and surface features. Along the south the area many hills that stand up above the general southward. The Ozark region consists of two areas, a north ern border of the Ozark Plateau, at a higher eleva level and are locally known as mountains. The DRAINAGE. ern and a southern, which differ greatly in size, in tion, stands a much dissected region known as the tops of most of these hills are flat, of small area, the nature of the rocks at the surface, and in sur Boston Mountains, which form the southern as well and stand from 500 to 1000 feet above the adjacent General statement. The streams of the quad face features. The northern and larger of these as the highest part of the Ozark region. Their valleys. Among these are Weedy Rough Moun rangle flow northward, westward, southwestward, areas is the Ozark Plateau, and the southern is the average width north and south is about 35 miles, tain, Henderson Mountain, GaylOr Mountain, and southward. The water of about one-sixth of Boston Mountains. The Winslow quadrangle lies and they extend east and west approximately 200 Cartwrigbt Mountain, Meadow Mountain, Lockard the area passes into White River through West and in the Boston Mountains, its exact location being miles, from Grand River, in Indian Territory, to Mountain, Kimes 'Mountain, Bald Knob, Chinka Middle forks of that stream, the remainder into shown in fig. 1. the Tertiary lowlands of eastern Arkansas. The pin Knob, Grapevine Knob, and others. ' the Arkansas. The water divide is a crooked highest part whose altitude has been determined is The highest part of the area is near the eastern though well-defined line passing from Sunset, near THE OZARK PLATEAU. about in the middle of the east-west extent of the border, at the villageH 6f Sunset, which is somewhat the eastern border, through Winslow, thence north Location and surface features.

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