Holmes's Notes on the Geology of Charleston. 19 f 



between the alluvium and diluvium, (if both are here,) I shall net 

 attempt, but leave it to more skillful hands, with a single remark. 



At Ashley ferry, ten miles N.W. of Charleston, the stratum of 

 red, or " iron-ore clay," with its thin seam of grey sand, is expo- 

 sed in a section of the river bank, resting immediately upon the 

 Eocene marl, while under the city a bed of Post-pliocene inter- 

 venes. I infer this to be the same as the deposit of clay in 

 Georgia, of which Mr. Lyell speaks, and from which he obtained 

 the grinder of the mastodon, and Dr. Habersham bones of that 

 and other extinct mammalia. Mr. Lyell represents it as " rest- 

 ing immediately on sand containing marine shells of living spe- 

 cies," which sand, I should infer, corresponds with the Post-plio- 

 cene bed of South Carolina. 



I have never found any teeth or bones in this clay, but frag- 

 ments of the grinders of the mastodon, with gravel and drift from 

 the river lodged in the holes of the surface of the Eocene marl 

 exposed in the bed of the river, have often been found by myself 

 and friends, and it is quite reasonable to infer that they were 

 washed out of the clay by the current. Some years ago I found 

 portions of a large bone which I supposed to be a femur of a 

 mastodon or other large mammalian, in a cavity on the surface of 

 a Post-pliocene bed, with the clay immediately above it. These 

 specimens are now in my cabinet. 



The next in the order of descent is the blue mud and sands, 

 with shells of the Post-pliocene formation, to which allusion has 

 just been casually made. This is the newest of the tertiary ; 

 sometimes the blue mud is missing, and laminated sands and 

 clays are mixed with or cover the beds of shells. 



The testacea of this bed, whose analogues are supposed by Mr. 

 Lyell and some other geologists, to be those now living in the 

 neighboring waters, lie in patches filling the depressions and ir- 

 regularities of the surface of the Eocene marl, upon which they 

 are always found immediately to rest. I say always, because I 

 have never seen the Miocene underlying the Post-pliocene in the 

 order of superposition, but in every exposure that I have examined, 

 the Eocene has been so found. 



The two Miocene deposits near Charleston, are covered either 

 w ith diluvial sands, or the alluvium of the rivers ; whence I infer, 

 that during the deposition of the Post-pliocene, these patches of 

 Miocene must have been above water, or were denuded of their 

 Post-pliocene covering previous to the deposition of the diluvial 

 °r alluvial sands and clays. 



With but a single exception, the Post-pliocene is never above 

 the level of high water. In a well dug on the side of a run, 

 a bout a quarter of a mile inland from Ashley ferry, and ten miles 

 N.W. of Charleston, shells of this formation have been exposed. 

 I accompanied Professor Tuomey, late state geologist, in the ex- 



