Abstract

Hamakhtesh Hagadol is an erosional cirque (a makhtesh) located in the northern Negev Desert. The Matmor Formation (Callovian, Middle Jurassic) is exposed in Hamakhtesh Hagadol and contains fossils from a Jurassic equatorial shallow marine environment. The fossils and rock samples in this study were collected from multiple sections. Bivalves, gastropods, sponges, corals, echinoderms, and sclerozoans are present in these sections to varying degrees. The preservation of the fossils ranges from original and recrystallized hard parts to internal and external molds. This project also incorporates previous studies conducted in the Matmor Formation by College of Wooster students. This study is the first to combine all the paleontological data into one report. As a result there are a total of six phyla, ten classes, twenty-four orders, fifty-eight known genera, and fifty-seven known species, as well as numerous unknown sponges and corals, within the Matmor Formation. The fossils from the Elyssa-2 section form two successive communities: The earlier Diverse Echinoderm Community and the later Diverse Mollusk Community. The Diverse Echinoderm Community is found in two subunits (E2-2 and E2-3) which have the highest abundance and diversity of echinoderms. The environment of the Diverse Echinoderm Community was a low energy environment with various pulses of increased sedimentation. The Diverse Mollusk Community is found in three subunits (E2-6 through E2-8) which have the highest abundance and diversity of bivalves and gastropods. This community was in a shallow water environment above the wave base and shallower in depth than the Diverse Echinoderm Community. The substrate was composed of a mixture of fine-grained and coarse-grained sediment that allowed for both epifaunal and infaunal organisms. The fine-grained sediment allowed deposit-feeding organisms to thrive while the coarse-grained sediment allowed suspension-feeding organisms to thrive. The stratigraphy of the Elyssa-2 through Elyssa-5 sections consists of alternating layers of marl and limestone indicating changes in sea level caused by local small-scale regressions. Normal faulting is present in the Matmor Formation and was contemporaneous with deposition.

Advisor

Wilson, Mark

Department

Geology

Disciplines

Paleontology

Publication Date

2009

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2009 Elyssa Belding