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Earth Sciences

William & Mary

Dissertations, Theses, and Masters Projects

Theses/Dissertations

1993

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

The Structure Of The Holocephalan Head And The Relationships Of The Chondrichthyes, Eileen D. Grogan Jan 1993

The Structure Of The Holocephalan Head And The Relationships Of The Chondrichthyes, Eileen D. Grogan

Dissertations, Theses, and Masters Projects

The interrelationship of the chondrichthyan subclasses is evaluated based on divergence in the nature of the suspensorium, the preorbital cranial anatomy, the distribution of major venous sinuses and localization of hematopoietic tissue. The anatomy of representative extant taxa was examined by radiography and/or dissection. Fossil selachians, paraselachians, and holocephalans of the Bear Gulch of Montana, U.S.A. (Mississippian, Namurian E2B) were studied for evidence of vascular pigmentation, suspensorium, and cranial, branchial, and pectoral anatomy. These studies validate the suspensorial condition of autodiastyly and suggest autodiastyly is a fundamental condition involved in the basic radiation of Chondrichthyes. The plesiomorphous condition of all …


Suspended Sediment Concentration Profiles In The Bottom Boundary Layer, Jingping Xu Jan 1993

Suspended Sediment Concentration Profiles In The Bottom Boundary Layer, Jingping Xu

Dissertations, Theses, and Masters Projects

Near-bottom suspended sediment concentrations and velocities were measured on the inner shelf off Duck, N.C. from late October to early November, 1991. This period embraced both fair and storm conditions. Four bottom roughness models are tested using field data together with a wave-current boundary layer model. Bottom roughness plays a significant role in calculations of sediment concentration profiles and current velocity profiles. The importance of each of the three parts in the roughness models (grain roughness, ripple roughness, and sediment motion roughness) vary depending on forcing conditions. A new bottom roughness model is established and tested. The calculated concentration and …