Date of Award

1974

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Geology

First Advisor

Dr. Frank R. Karner

Abstract

Geologists, particularly stratigraphers and sedimentologists, utilize terms to describe bedding thicknesses such as "thin", “medium" and "thick" that are poorly defined. Kelley, who discussed the early unsuccessful attempts to define bedding, believed that such terms should have an accepted meaning through the establishment of standard thickness divisions.

Kelley introduced the stratification index as a means of creating these divisions. He believed that the index would be a useful method of expressing quanitatively the difference in beddeness of units, members and formations.

Stratification index =- Number of beds x 100/Total thickness

In this paper the stratification index is used in the comparison of formations, informal members end lithologies between and among the Leatham and Madison Formations of Mississippian age in northeastern Utah and the Sappington and Lodgepole Formations of Mississippian age in southwestern Montana , Holland (1952). In addition, the stratification index of silt and clay beds in a section of Pleistocene Lake Agassiz sediments of Quaternary age in the "Mayville Ditch" in eastern North Dakota. A description of each Mississippian formation includes the location and type of lithologies in the formation and stratigraphic relationships of the formation. The Pleistocene section description includes location, and types of sediment.

Results and raw data from the study are expressed in bar graphs, a summary table, and the appendix.

Interpretation of bed thicknesses was neccesary to obtain an average bed thickness. Holland's accurate descriptions and measurements enabled the author to make an almost complete picture of each formation.

Limestones were found to be the best indicator of the apparent resistance of three upper informal members of the Madison Formation of Utah. The overal1 stratification index gives a false idea of the strata resistance.

The Madison Formation is thickerbedded than the Leatham Formation because the “thicker-bedded" Madison limestone makes up a large part of its thickness while the "thinner-bedded" Leatham ahales make up a large part of the bed but a small part of the thickness.

The Leatham Formation of Utah is “thicker-bedded” than the Sappington Formation of Montana because the Sappington shales make up a greater number of the beds and a larger part of the thickness than the Leatham shales do.

The Sappington Formation is “thinner- bedded” than the Lodgepole Formation because the majority of the beds and thickness of the Lodgepole are limestones which are "thicker-bedded" than the shales that make up the majority of the beds and thickness of the Sappington.

The limestones of the Madison Formation of Utah are “thicker-bedded” than the limestones of Lodgepole Formation of Montana.

The silt beds which make almost all of the “Mayville Ditch" section are about 61/2 times thicker than the clay beds on the average.

Since Kelley's introduction of the stratification index in 1956, there has no application of the index in stratigraphic literature. The application of the stratification index to Holland (1952) is the first application, to the author' s knowledge, of the stratification index to a field problem.

The stratification index may be a useful method of expressing quanitatively the difference in beddedness of units, members, and formations. The strat. index can also be used in establishing numerical limits for environmental conditions, and careful indices determination may enhance facies studies for a formation.

Stratification facies (phyllofacies?) and isostraitification (isobed) maps may be used with other types of maps or alone in determination of enviroments. If these methods are adopted, and data accumulates some useful facts of stratification will appear.

Geologists, particularly stratigraphers and sedimentologists, utilize terms to describe bedding thicknesses such as "thin", “medium" and "thick" that are poorly defined. Kelley, who discussed the early unsuccessful attempts to define bedding, believed that such terms should have an accepted meaning through the establishment of standard thickness divisions.

Kelley introduced the stratification index as a means of creating these divisions. He believed that the index would be a useful method of expressing quanitatively the difference in beddeness of units, members and formations.

Stratification index =- Number of beds x 100/Total thickness

In this paper the stratification index is used in the comparison of formations, informal members end lithologies between and among the Leatham and Madison Formations of Mississippian age in northeastern Utah and the Sappington and Lodgepole Formations of Mississippian age in southwestern Montana , Holland (1952). In addition, the stratification index of silt and clay beds in a section of Pleistocene Lake Agassiz sediments of Quaternary age in the "Mayville Ditch" in eastern North Dakota. A description of each Mississippian formation includes the location and type of lithologies in the formation and stratigraphic relationships of the formation. The Pleistocene section description includes location, and types of sediment.

Results and raw data from the study are expressed in bar graphs, a summary table, and the appendix.

Interpretation of bed thicknesses was neccesary to obtain an average bed thickness. Holland's accurate descriptions and measurements enabled the author to make an almost complete picture of each formation.

Limestones were found to be the best indicator of the apparent resistance of three upper informal members of the Madison Formation of Utah. The overal1 stratification index gives a false idea of the strata resistance.

The Madison Formation is thickerbedded than the Leatham Formation because the “thicker-bedded" Madison limestone makes up a large part of its thickness while the "thinner-bedded" Leatham ahales make up a large part of the bed but a small part of the thickness.

The Leatham Formation of Utah is “thicker-bedded” than the Sappington Formation of Montana because the Sappington shales make up a greater number of the beds and a larger part of the thickness than the Leatham shales do.

The Sappington Formation is “thinner- bedded” than the Lodgepole Formation because the majority of the beds and thickness of the Lodgepole are limestones which are "thicker-bedded" than the shales that make up the majority of the beds and thickness of the Sappington.

The limestones of the Madison Formation of Utah are “thicker-bedded” than the limestones of Lodgepole Formation of Montana.

The silt beds which make almost all of the “Mayville Ditch" section are about 61/2 times thicker than the clay beds on the average.

Since Kelley's introduction of the stratification index in 1956, there has no application of the index in stratigraphic literature. The application of the stratification index to Holland (1952) is the first application, to the author' s knowledge, of the stratification index to a field problem.

The stratification index may be a useful method of expressing quanitatively the difference in beddedness of units, members, and formations. The strat. index can also be used in establishing numerical limits for environmental conditions, and careful indices determination may enhance facies studies for a formation.

Stratification facies (phyllofacies?) and isostraitification (isobed) maps may be used with other types of maps or alone in determination of enviroments. If these methods are adopted, and data accumulates some useful facts of stratification will appear.

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