Editing Louisiana (section)

===Geology===
{{Main|Mississippi River Delta}}
The oldest rocks in Louisiana are exposed in the north, in areas such as the [[Kisatchie National Forest]]. The oldest rocks date back to the early [[Cenozoic Era]], some 60 million years ago.<ref>{{cite book |last=Spearing |first=D. |year=1995 |title=Roadside Geology of Louisiana |publisher=Mountain Press Publishing Company |location=[[Missoula, Montana]] |pages=5–19 }}</ref> The youngest parts of the state were formed during the last 12,000 years as successive deltas of the Mississippi River: the [[Maringouin, Louisiana|Maringouin]], [[Bayou Teche|Teche]], [[St. Bernard Parish, Louisiana|St. Bernard]], [[Bayou Lafourche|Lafourche]], the modern Mississippi, and now the [[Atchafalaya River|Atchafalaya]].<ref>{{cite journal |last1=Coleman |first1=J. M. |author2=H. H. Roberts |author3=G. W. Stone |date=1998 |title=Mississippi River Delta: an overview |journal=Journal of Coastal Research |volume=14 |pages=698–716 }}</ref> The sediments were carried from north to south by the Mississippi River.

Between the tertiary rocks of the north, and the relatively new sediments along the coast, is a vast belt known as the [[Pleistocene]] Terraces. Their age and distribution can be largely related to the rise and fall of sea levels during past ice ages. The northern terraces have had sufficient time for rivers to cut deep channels, while the newer terraces tend to be much flatter.<ref>{{cite journal |last=Holland |first=W.C. |date=1944 |title=Physiographic divisions of the Quaternary lowlands of Louisiana |journal=Proceedings of the Louisiana Academy of Sciences |volume=8 |pages=10–24 }}</ref>

[[Salt dome]]s are also found in Louisiana. Their origin can be traced back to the early [[Gulf of Mexico]] when the shallow ocean had high rates of evaporation. There are several hundred salt domes in the state; one of the most familiar is [[Avery Island, Louisiana]].<ref>{{cite book |last1=Kniffen |first1=F. B. |author2=S. B. Hilliard |date=1988 |title=Louisiana: Its Land and People |edition=Revised |publisher=Louisiana State University Press |location=Baton Rouge |pages=66–68 }}</ref> Salt domes are important not only as a source of salt; they also serve as underground traps for oil and gas.<ref>{{cite book |last=Spearing |first=D. |year=1995 |title=Roadside Geology of Louisiana |publisher=Mountain Press Publishing Company |location=[[Missoula, Montana]] |pages=19–30 }}</ref>