Miscellanies. 417 



" Perhaps the most difficult point to solve, is that which presents 

 itself in the fact, that deposits in high latitudes contain animal and 

 vegetable remains, presumed by analogy to be unable to exist in 

 their temperature at the present period. A change in the earth^s 

 axis, would, of course affect the temperature of its surface, but 

 whether that can take place under any known law in a sufficient de- 

 gree to effect such a change, has certainly not been established. Sir 

 John Herschel, has supposed that a change of temperature might 

 take place in the change of the elliptical orbit of the earth, which 

 becomes gradually more circular." 



The Tertiary deposit in particular, which has formed so rich a har- 

 vest for Mr. Lea, is situated at Claiborne, on the east side of the Al- 

 abama river, about ninety miles in a direct line from the Gulf of 

 Mexico. It was made known to him by Judge Tait, a citizen of that 

 place, in January 1829, from whom he received samples before the 

 close of the year, and in the year following, an additional supply, to- 

 gether with some notices of their mode of occurrence. These would 

 have been made public at an earlier period but for the occupation of 

 Mr. Lea, with the examination of recent shells. 



From Judge Tail's observations, it appears, that this formation which 

 at Claiborne, attains an elevation of two hundred feet, spreads through 

 the whole of South Alabama, (its southern edge commencing about 

 ten miles south of Claiborne bluff) and extends as it is believed 

 through the whole of the States of Alabama^ Mississippi, and ter- 

 minates only in the Chickasaw Bluffs of West Tennessee. 



The Alabama river passing under the bluff of Claiborne, reveals 

 a fine section for geological observations, of which no doubt Judge 

 Tait availed himself in the descriptions he gives of the successive strata. 

 Beginning at the bottom we are first presented with a bed having the 

 thickness of one hundred and twenty feet, which Mr. L. calls a soft 

 calcareous rock, through which are occasional scales of mica and 

 sprinklings of calcareous matter together with numerous fragments of 

 shells consisting generally of Flustrce, Cardice, Corbulce, Ostra, 

 Volutce, JVaticce and Turritellm, but the fragments were too friable 

 and imperfect to admit of more satisfactory determination. He hes- 

 itates whether, upon this amount of information to include it in the 

 Tertiary, or to refer it to an earlier origin. The next stratum in the 

 ascending series, and which is closely related to the foregoing, is a 

 more compact calcareous rock containing micaceous grains of dark 

 green sand, a single and imperfect valve of a large O&trea, a Teredo 



Vol. XXV.— No. 2. 53 



