Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
Articles 1 - 6 of 6
Full-Text Articles in Geology
Were All Devonian Seeds Cupulate? A Reinvestigation Of Pseudosporogonites Hallei, Xenotheca Bertrandii, And Aglosperma Spp., Cyrille Prestianni, Jason Hilton, Walter L. Cressler
Were All Devonian Seeds Cupulate? A Reinvestigation Of Pseudosporogonites Hallei, Xenotheca Bertrandii, And Aglosperma Spp., Cyrille Prestianni, Jason Hilton, Walter L. Cressler
Earth & Space Sciences Faculty Publications
No abstract provided.
Late Devonian Spermatophyte Diversity And Paleoecology At Red Hill, North-Central Pennsylvania, U.S.A., Walter L. Cressler Iii, Cyrille Prestianni, Ben A. Lepage
Late Devonian Spermatophyte Diversity And Paleoecology At Red Hill, North-Central Pennsylvania, U.S.A., Walter L. Cressler Iii, Cyrille Prestianni, Ben A. Lepage
Earth & Space Sciences Faculty Publications
No abstract provided.
Plant Paleoecology Of The Late Devonian Red Hill Locality, North-Central Pennsylvania, An Archaeopteris-Dominated Wetland Plant Community And Early Tetrapod Site., Walter L. Cressler Iii
Plant Paleoecology Of The Late Devonian Red Hill Locality, North-Central Pennsylvania, An Archaeopteris-Dominated Wetland Plant Community And Early Tetrapod Site., Walter L. Cressler Iii
Earth & Space Sciences Faculty Publications
The Late Devonian Red Hill locality in north-central Pennsylvania contains an Archaeopteris-dominated plant fossil assemblage, a diverse fossil fauna, and an extensive sedimentary sequence ideal for investigating the landscapes and biotic associations of the earliest forest ecosystems. Sedimentological analysis of the main plantfossil bearing layer at Red Hill indicates that it was a fl ood-plain pond. A seasonal wet-and-dry climate is indicated by well-developed paleovertisols. The presence of charcoal interspersed with plant fossils indicates that fi res occurred in this landscape.Fires appear to have primarily affected the fern Rhacophyton. The specifi city of the fires, the distribution profi …
A Late Devonian Isoetalean Lycopsid, Otzinachsonia Beerboweri Gen. Et Sp Nov., From North-Central Pennsylvania, Usa, Walter L. Cressler, H W. Pfefferkorn
A Late Devonian Isoetalean Lycopsid, Otzinachsonia Beerboweri Gen. Et Sp Nov., From North-Central Pennsylvania, Usa, Walter L. Cressler, H W. Pfefferkorn
Earth & Space Sciences Faculty Publications
No abstract provided.
Inclusive Chemical Characterization Of Tourmaline: Mossbauer Study Of Fe Valence And Site Occupancy, M D. Dyar, M E. Taylor, Tim Lutz, C A. Francis, C V. Guidotti, M Wise
Inclusive Chemical Characterization Of Tourmaline: Mossbauer Study Of Fe Valence And Site Occupancy, M D. Dyar, M E. Taylor, Tim Lutz, C A. Francis, C V. Guidotti, M Wise
Earth & Space Sciences Faculty Publications
We report here the results of a series of inclusive chemical characterizations, including all elements except oxygen, for a suite of 54 tourmaline samples. A combination of analytical techniques was used to analyze for major and light elements (electron microprobe), Fe3+ and Fe2+ (Mossbauer spectroscopy), H (U extraction), and B, Li, and F (ion microprobe, or SIMS). The B content of the tourmalines studied ranges from 2.86 to 3.26 B per formula unit (pfu) with 31 anions; excess boron is believed to reside in the Si site. Li ranges from 0.0 to 1.44 Li pfu and F contents are 0.0-0.91 …
An Improved Method For Determining And Characterizing Alignments Of Point-Like Features And Its Implications For The Pinacate Volcanic Field, Sonora, Mexico, Tim Lutz, J T. Gutmann
An Improved Method For Determining And Characterizing Alignments Of Point-Like Features And Its Implications For The Pinacate Volcanic Field, Sonora, Mexico, Tim Lutz, J T. Gutmann
Earth & Space Sciences Faculty Publications
We present an improved method for determining statistically significant alignments of pointlike features. One of the principal such methods now in use, the two-point azimuth method, depends on a homogeneous distribution of points over the region of interest. Modification of this approach by use of the relatively new statistical technique of kernel density estimation permits treatment of heterogeneous point distributions without introducing substantial dependence on choice of the grid employed in the test for significance of apparent preferred orientations. The improved method can selectively reveal alignments on different spatial scales and can suggest the locations of alignments as well as …