252 THE IRON ORE DISTRICT OF EAST TEXAS. 



NOTES ON THE STRATIGRAPHY OF SHELBY COUNTY. 



The following section, taken from the ferry road on the Louisiana side of 

 the Sabine River, at Logan sport, Louisiana, shows a probable rearrangement 

 by transportation of the members of the section above No. 7. 



1. Gray sandy soil 2 feet. 



2. Mottled yellow and gray clay 10 feet. 



3. Yellow and blue clay interstratifled ... 4 feet. 



4. Greode iron formation (nonconformable) 1 foot. 



5. Sandy clay 3 feet. 



6. Iron sandstone (irregular). 1 foot. 



7. Lignitic shale to water line 2 feet. 



Passing from Logansport to Timpson the surface is gently rolling. In 

 the railway cuts through the ridges the strata are clay and sand interstrati- 

 fled, with occasional thin crusty seams of ferruginated material near the top 

 and projecting about an inch from the weathered incline of the cuts. The 

 capping of the ridges is usually red sandy clay, with some small fragments 

 of iron sandstone remaining. The dip of the strata is generally east by 

 south about 5° to 8°. In one cut, about three miles northeast of Timpson, 

 was seen a siliceous limestone slab six inches thick and two feet exposure. 



At Teneha, at Timpson, at Center, at Patroon, and elsewhere, as already 

 stated, magnetic iron pebbles and magnetic iron gravel were seen, associated 

 with similar pebbles and gravel which were non-magnetic. 



The iron pebbles were derived from the disintegration of the iron con- 

 glomerate, and the iron gravel from the breaking up of the laminated ore, 

 the buff crumbly ore, and concentric crusts of the geode ore. 



The partial magnetization of the iron pebbles and iron gravel is attribut- 

 able to the action of local forest fires, causing dehydration, partial reduction 

 of the sesquioxide to protoxide of iron. 



In the dump from one of the public wells at Timpson a few small fragments 

 of bright lemon-yellow ochre were seen. 



In the road, five and one-half miles north of Timpson, one mile west of 

 Cave Spring Hill, were seen bowlders of iron conglomerate about two feet in 

 thickness. 



A similar conglomerate was seen at a little bridge an eighth of a mile south 

 of Timpson. 



The Cave Spring Ridge section of the iron ore deposit has already been 

 given. 



Iron sandstone was seen on ridges seven miles south of Timpson, and on 



