1895.] NATURAL, SCIENCES OF PHILADELPHIA. 133 



ing west the line continues in a west by south direction to near 

 Brownsboro, in Henderson, and thence south to the Trinity near the 

 south line of Anderson, and from there in a southwesterly direction 

 to the Brazos. Throughout the northeastern portion of the state 

 isolated hills covered by deposits of the same age occur' in some of 

 the counties. These, however, are usually unfossiliferous and of no 

 great extent. 59 The main body of the beds occupies a position in 

 the form of an inverted V, being widest at its apex, where a line 

 drawn across them from Bullard through Jacksonville, Rusk and 

 Alto measures over forty miles. From this line they gradually narrow 

 both to the west and east until on the Brazos the width does not ex- 

 ceed thirteen miles, and on the Sabine not more than seven or eight. 



The dip of these beds appears to be in an inverse ratio to the 

 width — that is to say it is greater on the Brazos than farther east, 

 and gradually becomes less as we approach the Sabine. While the 

 great or general dip of the whole of these deposits is toward the 

 gulf they have apparently been subjected to pressure from the south 

 or southeast as in many places slight waving or undulations occur 

 that give the beds the appearauce of dipping toward the northwest 

 in many places. These uudulatious are greater in the basal division 

 or " Mount Selman series," and pass into the underlying lignitic. A 

 very good type of this formation may be seen in Mount Selman it- 

 self as that mountain forms the bottom of a synclinal trough. They 

 do not appear in the Yegua clays or succeeding deposits, and whether 

 they affect the cretaceous beds or not is not known with any degree 

 of certainty, although it is generally assumed that they do to some 

 small extent. 



The topography of the country occupied by the Marine beds may 

 be described as an elevated plateau rising abruptly from the plane 

 of the surrounding beds to an average elevation of five hundred feet 

 above sea level, although some of the higher "mountains" reach 

 elevations of over seven hundred feet. This plateau is so intersected 

 by the different rivers flowing across it and their subsidiary drainage 

 channels that it presents a much broken surface showing as narrow- 

 topped, steep-sided, ridges in many places and wide flat-topped hills 

 in others. This variation is chiefly due to the covering of the differ- 

 ent localities. When sand forms the prevailing material the ridges 

 are narrow and the reverse is the rule where we find the iron ore 



59 Science, Vol. XXIII, No. 571, pp. 22-25. 



