Pages 116-125
Contents
Bone From a Dry Sea Pages 116-125
Summary
The excerpt begins with Vinny telling Watson about the sea-ape theory, which prompted Watson to ridicule Vinny's father because Watson thought the theory was nonsense. Then Vinny, attempts to distract Watson for her father and the shell fragments she tries to distract him with turns out to have three scratch marks on one side of the fracture. Vinny, Watson, and Dr. Hamiska think that the scratches were made by a primitive human, but Vinny's dad is a doubter. Vinny and her father discuss the scratch marks on the unknown animal's scapula, but Vinny decides to not tell Dr. Hamiska right away because she does not like him calling her a good luck charm.
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and stratification. It is mostly used in the study or igneous and sedimentary rocks. Stratigraphy was established by Nicholas Steno, who introduced the Law of Superposition in 1669. Stratigraphy has 4 branches:
- Biostratigraphy: This branch of stratigraphy focuses on fossil evidence on rock layers, and strata (rock layers) that contain the same flora or fauna may be from the same time period.
- Lithologic stratigraphy: This branch focuses on the rock type change vertically due to different materials being deposited or different climates when the deposition was occurring.
- Chronostratigraphy: This branch deals with the absolute age of rock layers (a date like 1.3 million years ago). This can be used to compare different rock layers.
- Magnetostratigraphy: This branch uses the direction that tiny minerals orient themselves to determine the direction of the Earth's magnetic poles when the rock layer was deposited. For example, the rocks' magnetic orientation on the sides of rift valley's change, suggesting that not all rocks in that area were produced at the same time.
Archeological Techniques
"Vinny focused the magnifying glass on the outside of the fragment, near one edge, where she'd seen the others looking so intently" (122).
"She took the pieces and sorted that through. There were two more from one of the larger creatures, and one of them fitted exactly onto a piece she already had. Now, from the curving growth-lines, she could see how the others might go" (120).
"The H-layer was important- it was the one which had the hominid fossils in it, immediately above the tuff" (118). * Note here that stratigraphy and the Law of Superposition was used here to determine the relative age of the H-layer.
"By lunchtime there was a large awning erected at the bottom of the hill, and a little one a few yards along from where Dad was working, to shade a second trench" (116).
