Tertiary Texas!
Dave Grant, Ocean Institute - Sandy Hook, NJ
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Our objective was to study lower Eocene outcrops along the Colorado River in Bastrop. Locked in these sediments is evidence of Paleocene-to-Eocene Climatic Events that some researchers say are related to the Earth's 100,000 year-long orbital eccentricities reported by Milankovitch. |
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The deposits are primarily sedimentary layers that include river terraces, sandstone, carbonaceous sand, silt, beach sand, lignite and mudstone. The layers demonstrate a transgressive sequence of rising sea levels that have covered much of coastal Texas over the last 55-million years. |
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A tense moment and potential traffic jam near the river is defused when our mission is explained. |
| Evidence of biological activity in marine sediments: The fossilized burrows of crustaceans Thalassinoides and Ophiomorpha. |
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 Argiope aurantia |
Local biological curiosities included spiders weaving webs (Left), and great masses of resting daddy-long-legs under cool shaded ledges (Below). |
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 Moths resting during the heat of the day. |
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 Botanical curiosities included lichens, poison oak sedges and an assortment of famous Texas wildflowers. |
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 Bio-hazard: Dave's heel after an encounter with fire ants. |
 Cliff swallows helped manage the insect population near the river. |
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