408 REPORT OB 1 NATIONAL MUSEUM, 1904. 



7. That the submerged stumps of trees found below the level of high tide along 

 the coast are not the result of subsidence, properly so called, but must be referred to 

 the encroachment of the sea upon the land and to the peculiar character of the 

 deposits in which they grew. 



8. That the almost entire absence of fluviatile shells in the recent and Tertiary 

 deposits is mainly due to two facts: (1) That there is a considerable space between 

 the line of brackish and salt water, where neither fluviatile nor marine forms can 

 exist; (2) that the streams have not transporting power sufficient to bring down 

 fresh-water shells. So long as these circumstances exist, there can be no mixture of 

 fluviatile and marine shells. 



Prior to 1848 the professor of geology in the State University of 

 Alabama had been required to spend a portion of his time, not exceed- 

 ing - four months of each year, in making geological explorations in 

 the State. ' In January, 1848, the general assembly, in 

 Alabama!* 1848-50° recognition of the utility of this work, passed a resolu- 

 tion appointing Michael Tuomey, then holding this 

 professorship, State geologist, and requiring him to make a report to 

 the general assembly at each of its biennial sessions. Thus simply was 

 inaugurated the first systematic geological survey of the State. 



Under this law, Tuomey's First Biennial Report, in form of an octavo 

 volume of 176 pages and a colored geological map of the entire State, 

 appeared in 1850. In this the rocks of the State were divided into 

 those of (1) The Primary, (2) Metamorphic, (3) Silurian, (4) Carbon- 

 iferous, (5) Cretaceous, and (6) Tertiary systems, the last named being 

 represented, so far as then known, only by the Eocene. Much of 

 the report was taken up with economical considerations, particular 

 attention being paid to coal and iron. 



The second report of this survey appeared under the editorship of 

 J. W. Mallet, the publication having been delayed through the pro- 

 crastination of the Public Printer and Professor Tuomey's death, which 

 occurred in March, 1857. 



. Tuomey recognized on Marble Creek in Limestone County a blue 

 limestone which was a continuation of the Silurian rocks in Tennessee. 

 The Devonian rocks were represented by black slate found on the 

 principal streams flowing from the north into the Tennessee between 

 Flint River in Madison and Shoal Creek in Lauderdale County. He 

 regarded the divisions of the carboniferous made by Troost as suffi- 

 ciently characteristic in north Alabama to be retained. 



The clastic material — that is, the loosely consolidated sands and 

 gravels — which he mapped as extending across the middle of the State 

 and north of the verge of the Cretaceous beds, and colored as post- 

 Tertiary, were referred to as belonging to the drift, although having 

 little resemblance to that of the north. "If the southern drift be at 

 all connected with that of the north," he wrote, k 'itmay be explained 

 by supposing that the northern glaciers suddenly melted, and that the 

 water thus liberated in immense volume took a southern direction, 



