THE ALTAMAHA GRIT REGION IN DETAIL. 

 Location and Boundaries. 



Up to 25 years ago the particular region under consideration 

 seems to have been entirely unknown to science. In 1881 Dr. 

 E. W. Hilgard 1 published a geological map of a part of the coastal 

 plain of the southeastern states, showing among other things 

 a few thousand square miles of " Miocene (?) sandstone" in south- 

 eastern Georgia, corresponding for the most part with what we 

 now know as the Altamaha Grit region. There is no reference to 

 this area in the accompanying text, but it was probably in- 

 serted on the authority of Dr. R. H. Loughridge, who was about 

 that time making a geological and agricultural survey of Georgia 

 for the U. S. Census office. In Dr. Loughridge's report, published 

 in 1884 in the 6th volume of the final reports of the Tenth Cen- 

 sus, the area of this "sandstone" was mapped in more detail, 

 and some outcrops of it were described. Its geological posi- 

 tion was also recognized. 



The name Altamaha Grit was given to the formation by Dr. 

 W. H. Dall 2 in 1 89 2, v after it had been studied along the Ocmulgee 

 and Altamaha rivers by Mr. Frank Burns, of the U. S. Geo- 

 logical Survey. But its boundaries were very imperfectly known, 

 mostly on account of the great scarcity of outcrops, until inves- 

 tigated from a phytogeographical standpoint by the writer in the 

 summer of 1903 3 and spring of 1904. And in the latter 

 year Mr. S. W. McCallie of the Geological Survey of Georgia 

 also became interested in it, and discovered some additional out- 

 crops of the characteristic rock, particularly in Johnson 

 County. 



Our present knowledge of the areal distribution of this and 

 other geological formations of the coastal plain of Georgia (omit- 

 ting subdivisions of the Cretaceous and Eocene) is shown on the 



1 Am. Jour. Sci. III. 22; pi. 3. 



2 Bull. U. S. Geol. Surv. 84: 81. 



3 See Bull. Torrey Club 32: 141-147. 1905. 



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