Changes

[[file:applied-paleontology_fig17-26.png|thumb|300px|{{figure number|4}}Paleontologic and paleoenvironmental variables across a condensed section in the Upper Eocene at St. Stephens Quarry, Alabama. Copyright: Loutit et al.;<ref name=ch17r60 /> courtesy SEPM.]]

[[file:applied-paleontology_fig17-26.png|thumb|300px|{{figure number|4}}Paleontologic and paleoenvironmental variables across a condensed section in the Upper Eocene at St. Stephens Quarry, Alabama. Copyright: Loutit et al.;<ref name=ch17r60 /> courtesy SEPM.]]

The [[Definitions_of_depositional_system_elements#Maximum_flooding_surface|maximum flooding surface]] (which may in fact be a thin stratigraphic interval) marks the turn-around point from an overall deepening to an overall shallowing trend. Associated with this horizon may be a major condensed section, marked by the lowest [http://www.thefreedictionary.com/terrigenous\ terrigenous] input, the greatest water depth (approximately), and organic enrichment. This condensed section can provide important fossil age data on [[continental margin]]s<ref name=ch17r60>Loutit, T., S., Hardenbol, J., Vail, P., R., Baum, G., R., 1988, Condensed sections: the key to age determination and correlation of continental margin sequences, in Wilgus, C., K., Hastings, B., S., Kendall, C., G. St. C., Posamentier, H., W., Ross, C., A., Van Wagoner, J., C., eds., Sea-Level Changes: An Integrated Approach: SEPM Special Publication 42, p. 183–213.</ref> because it usually contains the greatest abundance of microfossils and the highest concentration of pelagic forms, such as [[Microfossils_in_exploration#Principal_microfossils|planktonic foraminifera]] and [[Calcareous_microfossils#Calcareous_nannofossils|calcareous nannofossils]]. Other condensed sections are also (but less commonly) found (1) at the top of depositional cycles within the lowstand wedge and (2) overlying individual lowstand fans.

The [[Definitions_of_depositional_system_elements#Maximum_flooding_surface|maximum flooding surface]] (which may in fact be a thin stratigraphic interval) marks the turn-around point from an overall deepening to an overall shallowing trend. Associated with this horizon may be a major condensed section, marked by the lowest [http://www.thefreedictionary.com/terrigenous\ terrigenous] input, the greatest water depth (approximately), and organic enrichment. This condensed section can provide important fossil age data on [[continental margin]]s<ref name=ch17r60>Loutit, T. S., J. Hardenbol, P. R. Vail, and G. R. Baum, 1988, Condensed sections: the key to age determination and correlation of continental margin sequences, in C. K. Wilgus, B. S. Hastings, C., G. St. C. Kendall, H. W. Posamentier, C. A. Ross,and J. C. Van Wagoner, eds., Sea-Level Changes: An Integrated Approach: SEPM Special Publication 42, p. 183–213.</ref> because it usually contains the greatest abundance of microfossils and the highest concentration of pelagic forms, such as [[Microfossils_in_exploration#Principal_microfossils|planktonic foraminifera]] and [[Calcareous_microfossils#Calcareous_nannofossils|calcareous nannofossils]]. Other condensed sections are also (but less commonly) found (1) at the top of depositional cycles within the lowstand wedge and (2) overlying individual lowstand fans.

[[:file:applied-paleontology_fig17-26.png|Figure 4]] illustrates paleontologic and paleoenvironmental variables across a condensed section in the upper Eocene at St. Stephens Quarry, Alabama. The condensed section corresponds to the unnamed blue clay. Overlying Eocene [[Red Bluff]] and [[Bumpnose Formation]]s are [[Sea_level_cycle_phase_and_systems_tracts#Highstand_systems_tracts|highstand systems tract]] deposits; the [[Pachuta]] and [[Shubuta Formations]] represent shelf margin and [[Sea_level_cycle_phase_and_systems_tracts#Transgressive_systems_tracts|transgressive systems tracts]].

[[:file:applied-paleontology_fig17-26.png|Figure 4]] illustrates paleontologic and paleoenvironmental variables across a condensed section in the upper Eocene at St. Stephens Quarry, Alabama. The condensed section corresponds to the unnamed blue clay. Overlying Eocene [[Red Bluff]] and [[Bumpnose Formation]]s are [[Sea_level_cycle_phase_and_systems_tracts#Highstand_systems_tracts|highstand systems tract]] deposits; the [[Pachuta]] and [[Shubuta Formations]] represent shelf margin and [[Sea_level_cycle_phase_and_systems_tracts#Transgressive_systems_tracts|transgressive systems tracts]].