OUTCROPS IX ALABAMA 75 



diminishes to 600 feet, and some irregular streaks of limestone are 

 shown. 



The next important strip is in Browns valley, the continuation of 

 Sequatchie valley of Tennessee, which enters Jackson from Marion of 

 that state. This lies beyond Sand mountain and extends southwest- 

 wiard through Jackson, INIarshall, and Blount counties, about 20 miles 

 northwest from Wills valley ; but in Blount county is Murphrees valley, 

 about midway between Browns and Wills, to which reference must be 

 made, as it marks the transition betv/een conditions at the east and 

 those so well marked at the west. 



The Fort Payne chert is about 300 feet thick in Murphrees valley, 

 The rather pure limestone already mentioned as occurring at several 

 localities in the upper part of the Fort Payne, here becomes so well 

 marked that Mr McCalley has divided the Fort Payne into the Tus- 

 cumbia above, about 175 feet, and the Lauderdale chert below, about 

 125 feet, these corresponding closely to the Lithostrotion and Protean 

 of Safford in southern Tennessee, the latter being that regarded in the 

 former chapter as equivalent to the upper portion of the Pennsylvania 

 Pocono. Here also the sandstones of the Bangor become so well de- 

 fined that Mr McCallej^ sets them off from the Bangor under the name 

 of Hartselle sandstones. Eastward one finds massive sandstones at the 

 base of the Bangor and Oxmoor and at one locality a limestone below 

 them. In this valley sandstones are at the top of the Hartselle, while 

 below them are limestones, shales, and sandstones. The Bangor lime- 

 stone, as defined by McCalley, is about 300 feet, consisting of inter- 

 stratified limestones and shales, while the Hartselle is not far from 

 150 feet.* 



Within Jackson and Marshall, in Browns valley, the Fort Wa3^ne is 

 from 225 to 300 feet thick, and the two divisions can be distinguished, 

 though not so sharply as in Blount county where the mass is thicker, 

 the Lauderdale being 175 to 225 feet, and the Tuscumbia 125 to 150 

 feet. Throughout this valley the Lauderdale is almost wholly chert, 

 while the Tuscumbia consists of cherty limestone. The total thickness 

 of the Bangor is 600 to 800 feet in Jackson and 500 to 600 feet in Mar- 

 shall, but the sandstone at the base is very irregular. The sandstones 

 may not be the upper but the bottom sandstones of the Hartselle, for in 

 Dorans cove, in northeastern Jackson, there is a 25-foot sandstone at 

 75 feet below the top of the limestone. In Blount county the Bangor 

 has 300 to 350 feet of limestone and calcareous shale, while the Hart- 

 selle is from 150 to 225 feet, with massive sandstones 5 to 80 feet on top, 



* Henry McCalley, vol. i, pp. 395 to 407. 



