Fisk apparently did not include the terrace deposits bordering the central alluvial plain in his estimate of the amount of sediments. Because of their great lateral extent and the variation in land slope along them, coastlines are much easier to trace on topographic maps than in field surveys where the field of view is limited. The large discontinuities within a sequence of terrace deposits should mark the advance of the sea over the land after each ice age.
Many attempts, none very convincing, have been made to correlate emerging coastlines with the chronology of glaciated regions.
THE TRACING OF EMERGED SHORE LINES
6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49
SHORE LINES ALONG THE ATLANTIC SEABOARD
An article on the correlation of coastal terraces (Cooke, 1930b) proposed defining and identifying terraces by their coastlines. Its abstract (p. 577) states that: 'The Pelistocene coastal terraces along the Atlantic coast of the United States are bounded by coastlines lying horizontally south of the glacial area and appearing to extend undeformed westward along the Gulf Coast to Texas . ." Later work has amply confirmed the essential horizontal nature of the coastlines along the Atlantic coast; the present work follows the coastlines of the Mississippi Embyment. The names of these ten terraces and the elevations of their coastlines, as currently accepted, are as follows :
TERRACES IN ALABAMA
This elevation has since been determined as that of the Okefenokee Terrace shoreline.
TERRACES IN THE MISSISSIPPI EMBAYMENT
ARKANSAS
LOUISIANA
The Morley terrace is well preserved in the southern part of the Puxico, Mo., quadrangle, where it slopes upward from 325 feet at Ash Hill, Fisk, Lakeview School and Cypress School to 360 feet at the shoreline in sections 21 and 22, T. 8 E., above which the land rises to 447 feet at Asherville, a quarter of a mile from the shore.
The western shore of an island in Morley Bay is near the 360-foot contour line of the Puxico quadrangle passing 1 mile west of Aid, 1 mile west of Greenwood School, and near Howell School. The Morley coast has not yet been traced along the Atlantic, although the terrace is represented there. Flat areas in South Carolina higher than the Hazlehurst Terrace (shoreline 275 feet) are probably remnants of the Morley Terrace.
In Georgia, the Morley Terrace should be sought in the unmapped area between the Okefenokee Swamp and Tifton, where it. The Morleyshoreline, mroceded, forms the boundary between the Dougherty Plain and the Tifton Upland (Cooke, 1925). Pleasant, Gadsden County, Fla., and north into Decatur County, Ga., is evidently the lower part of the Morley terrace unless.
A broad plain in western Escambia County, Ala., slopes from 360 feet at the north edge of the Huxford quadrangle southward across the Atmore quadrangle to 280 feet at the Florida line.
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49
NO. 10 MISSISSIPPI EMBAYMENT SHORE LINES — COOKE I3
The eastern coast followed the bluffs across the Tennessee and ]\Iissippi to the Gulf of Mexico, the coast of which at that time intersected the northern part of the parishes of Louisiana in West Florida. This coast of the Gulf is difficult to trace because the terrace there is a lot. The 275-foot shore crosses the quadrangle of Marmaduke, Ark., and separates Hazlehurst from the dissected Morley terrace to the northwest.
The Hazlehurst Coast runs almost due south for 50 miles along the west side of Crowley Ridge, in Craighead County, to Forest Hill in Saint Francis County, to the 275-foot contour line. That the bay east of the ridge, once the valley of the Ohio, was deeper than the western projection, the original valley of the Mississippi, is shown by figure 7, a profile across the Dee quadrangle in the latitude of Trumann. The Hazlehurst Terrace covers the entire Walnut Ridge, Ark., quadrangle except the northeast corner, where a short stretch of shoreline is shown.
The terrace and the shore extend over the adjoining Powhatan quadrangle, but the terrace slopes gently .. down to 250 feet at the southern end, to the grade of the .. drowned valley, and the shoreline lies against the bluff. Coharie Terrace {shoreline 215 feet).— The shore of Coharie Bay (fig. 8) was more curved. Two teeth near the head are separated by Crowley Ridge and the edges of the Hazlehurst Terrace.
The entrance to the eastern tooth, which faces the drowned valley of the St. Francis River across Poinsett County, Ark. stretch, is partially blocked by an island 15 miles long, the continuation of Crowley Ridge.
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 -2 go oin
The western prong was roughly rhombic, with one side running from Haynes in Lee County, Ark., to Newport in Jackson County;. From this cape the entrance to the western prong wandered the crooked shore past Stuttgart, Tomberline in Loneoke County, and Pine Bluff. From Pine Bluff the shore of Coharie Bay followed the right bank of Bartholomew Bayou to Warrentonin Lincoln County and thence southward to Paradise in Drew County, which seems a good place to leave.
In Louisiana the west coast of Coharie Bay has not been traced in detail. It appears to have extended not far west of the Ouachita River to Harrisonburg in Catahoula Parish. Here it met the broad entrance to the combined estuaries of Little River and Red.
The narrow lower reaches of the bay widened to 50 miles between Catahoula Lake and the opposite cape in West Feliciana Parish, La. The coastline at the head of the eastern point was very complicated because the old Ohio River (now the Mississippi) and the old Mis-. Construction of the Delta undoubtedly began while the bay was still underwater and continued after the Coharie Terrace emerged.
For example, at Walnut Grove Corner, near the center of the Dee, Ark., quadrangle, a 10-foot bluff rises above the 215-foot grade and extends northward for more than 2 miles. Southeast of Harrisburg on the same map, a 215-foot sheet hugs the base of Crowley Ridge.
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 Ozark Escarpment from Bradford (Augusta quadrangle) to the
GULF OF MEXICO
I was on my way to Lincoln County, Ark., between Meroney and South Bend, on my way to Lincoln County, Ark., between Meroney and South Bend, where the delta of the Arkansas River was 20 miles wide. Beyond the Mississippi Valley, another long, narrower bay extended up the drowned RedRiver Valley from Alexandria, La., to the front above Shreveport. The bays in western Arkansas County and eastern Jefferson County in Arkansas occupy former tidal marshes whose shores follow the 170-foot contour line on the Gillett Quadrangle.
The Sunderland appears to be the same as Fisk's (1938a, p. 56) Montgomery terrace, which lies within a former mouth of the Red. The withdrawal of the Gulf from 170 feet to a lower level drained the flooded valleys and exposed the Sunderland Terrace. Okefenokee Terrace (shoreline 145 feet).—The approximate location of the coast of Okefenokee Bay is shown in figure 12.
In Arkansas, tidal water stretched the White River farther north, near St. In Louisiana it followed the west side of the Ouachita Valley to Harrisonburg, across which it went southwest to the Gulf of Mexico.
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 The Okefenokee shore is very conspicuous on the map of the
28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 49
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 Bayou Bartholomew flows upon the Wicomico terrace at Bastrop,
At Harrisonburg the coast turned southwestward along the uplands west of Bushley Creek and Catahoula Lake, where it curved southeastward toward the vast Gulf of Mexico in Avoyelles Parish near LongBridge. In the western part of Evangeline Parish, the Gulf shoreline followed the boundary line between the "Montgomery Formation" and the "Prairie Formation" as mapped by Varvaro (1957, pi. 1). The eastern shore of Penholoway Bay lay not far east of the Mississippi River, from Grand Gulf, Miss., to a projecting cape at Alsen, about four miles north of Baton Rouge, where it met the Gulf.
The State Industrial School for Boys at Alsen (Scotlandville, La., quadrangle) is built on Penholoway Terrace near the shore of the bay, which winds eastward past Baker, standing on the Wicomic. Most of the city of Baton Rouge is built on the Penholoway Terrace, and the southern part descends to the lower terraces (Figure 18). The Penholoway Terrace was named by Cooke (1925, p. 24) after Penholoway Creek and Penholoway Bay (swamp) in Georgia.
Baton Rouge (fig. 18) marked the crossing of the Kansas City Southern Railway with the St. Crossed West of Cape Lafayette, the coast of the Gulf was very low; there is no conspicuous scarp separating the Talbot Terrace from the Penholoway. The coastline appears to curve north-westwards past Cankton (Carencro quadrangle) to the south corner of ChurchPoint.
Within the bay, the general contours of which are shown in Figure 19, the coastline is made very complicated by distributaries of the Red Sea. The name Talbot terrace dates to 1901, when Shattuck (1901, p. 103) applied it to a marine and estuarine terrace in Maryland with a coastline nearly 45 feet above sea level.
TEXAS
I4914 miles southeast of Baton Rouge, and at Delacroix, 3 miles south- 14 miles southeast of Baton Rouge, and at Delacroix, 3 miles southeast of St. In the western part of the bay drainage of the Red River built a long delta, now followed by Bayou Teche, from Port Barre past Leonville and Arneaudville to Breaux Bridge. Another distributary followed Bayou Fordoche from Morganza to Frogmore on Bayou Grosse (Fordoche quadrangle), and broader branches bordered the river from ]\Iorganza to the southeast corner of the New Roads quadrangle.
The west shore of Pamlico Bay follows the 25-foot contour line in the Carencro quadrangle for 6 miles, passing 3 miles east of Sunset. The name Pamlico Formation was used by Stephenson (1912, pp) for the Pleistocene beds along Pamlico Sound in North Carolina, the upper surface of which forms a low, nearly level plateau, the elevation of which nowhere exceeds 25 feet. ". 34;Pamlicoterrace" on an earlier page of the same volume, by William Bullock Clark, whose description was based on Stephenson's field.
At the end of the quiet stand at 25 feet, the Gulf retreated and . came to rest about 6 feet above its present level. A bay occupied the drowned drainage system in the Atchafalaya's farnorthasCatahoula (Loreauvillequadrangle), about 10 miles northeast of St. At the White Castle Oil Field (White Castle quadrangle) it was stopped by the Mississippi Delta, which formed the eastern boundary.
An exception is at Ponchatoula, where a bluff rises about 10 feet above the 5-foot contour line that borders the north shore of Marepas Lake. The shore of the Gulf during Silver Bluff time is marked by a narrow barrier beach, rising 10 feet above the 5-foot line, which turns into the southwest part of the Lake Charles quadrangle.
RESUME OF EVENTS
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 was kept fresh or only slightly brackish by the great volume of river
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49
