Spatial distribution of Miocene Foraminifera at Calvert Cliffs, Maryland

Related Titles

Series: Smithsonian contributions to paleobiology, no. 68

By

Buzas, Martin A.

Gibson, Thomas G.

Type

Book

Material

Published material

Publication info

Washington, D.C, Smithsonian Institution Press, 1990

Notes

Excavations made in middle Miocene strata in the Calvert Cliffs of Maryland during construction of a nuclear power plant were used for a spatial distribution study of fossil benthic foraminifera over large bedding surfaces. Two bedding surfaces were sampled, a larger and older one involving a 400 m2 surface in the Calvert Formation, and a slightly younger one involving a 50 m2 surface in the Choptank Formation. The sampling procedure for both surfaces consisted of a 3- <U+00D7> 3-station grid, with 5 replicates taken at each of 9 stations. The larger surface had stations at 9.5 m centers, and the smaller surface had stations at 3.6 m centers. The amount of variation in species proportions and densities from each bedding surface were used to determine how much confidence can be placed in the results from the usual paleontologic sampling procedure of a single sample. Unispecies and multispecies analyses were done on the 45 samples from each of the surfaces. The study of the older surface involved 36 species, and the younger 33. Analyses indicate a remarkable degree of homogeneity of species densities and proportions in both of these beds. Species usually remain in the same rank order at all stations within each surface, indicating that any of the 45 samples gives a reasonable species composition for the surface. Species densities exhibit greater variability; the determination of confidence limits for species densities requires multiple samples to reach limits of ±50 percent accuracy.

Excavations made in middle Miocene strata in the Calvert Cliffs of Maryland during construction of a nuclear power plant were used for a spatial distribution study of fossil benthic foraminifera over large bedding surfaces. Two bedding surfaces were sampled, a larger and older one involving a 400 m2 surface in the Calvert Formation, and a slightly younger one involving a 50 m2 surface in the Choptank Formation. The sampling procedure for both surfaces consisted of a 3- × 3-station grid, with 5 replicates taken at each of 9 stations. The larger surface had stations at 9.5 m centers, and the smaller surface had stations at 3.6 m centers.The amount of variation in species proportions and densities from each bedding surface were used to determine how much confidence can be placed in the results from the usual paleontologic sampling procedure of a single sample.Unispecies and multispecies analyses were done on the 45 samples from each of the surfaces. The study of the older surface involved 36 species, and the younger 33. Analyses indicate a remarkable degree of homogeneity of species densities and proportions in both of these beds. Species usually remain in the same rank order at all stations within each surface, indicating that any of the 45 samples gives a reasonable species composition for the surface. Species densities exhibit greater variability; the determination of confidence limits for species densities requires multiple samples to reach limits of ±50 percent accuracy.

Subjects

Calvert Cliffs , Foraminifera, Fossil , Maryland , Miocene , Paleontology

BHL Collections

Unearthed! Smithsonian Libraries' Paleo Collection

Call Number

QE701 .S56 no. 68

Language

English

Identifiers

DOI: https://doi.org/10.5479/si.00810266.68.1
LCCN: https://lccn.loc.gov/89600314
OCLC: 20492308