Hoyt and Hails (1974) . Figure 13 is a cross section through the Lower Coastal 

 Plain of Georgia showing relationships between the terraces. The cross sec- 

 tion is similar to that presented by Colquhoun (19-74) for central South Caro- 

 lina. In the vicinity of the North Carolina -South Carolina border, a similar 

 number of terraces in the Lower Coastal Plain, with similar elevations, have 

 been recognized by DuBar (1971). Terrace names in this locality differ from 

 those recognized by authors previously discussed; however, their mode and tim- 

 ing of formation are the same. The most seaward Pleistocene terrace is termed 

 Myrtle Beach. 



25. Elevation of terraces above present sea level suggests a progres- 

 sive, although episodic, drop in sea level since Miocene time. An alternative 

 explanation for elevation of the terraces above the modern coast is offered by 

 Cronin (1981) . According to Cronin, sediment loading in a Mesozoic/Cenozoic 

 trough 200 km seaward of the South Carolina coast could be resulting in corre- 

 sponding uplift of the Coastal Plain lithosphere in excess of 1 to 3 cm/ 

 1,000 years. This could have resulted in a 60-m uplift of the Orangeburg 

 Scarp since Miocene time and corresponding uplift of each of the terraces. If 

 some part of the elevation of terrace sediments is due to upward flexure of 

 the lithosphere, it would imply that the magnitude of eustatic changes in sea 

 level since Miocene would be less than presently supposed. 



Holocene 



26. Superimposed on the long-term (approximately 20 million years) 

 trend of falling sea level since Miocene time are Holocene sea level curves. 

 These curves generally show a worldwide rise in sea level during the last 

 15,000 years (Figure 14), with a decrease in rate of rise from 4,000 years BP 

 to present. Data collected by Colquhoun and Brooks (1986) show rise in sea 



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Figure 13. Lower Coastal Plain marine terraces (Hoyt and Hails 1974, 

 reprinted by permission) 



28 



