Answer to Question 1
Answer: Both samples are composed of the same minerals. However, the fragment from the wall of the volcano is the sample with minerals readily visible to the naked eye. It is very difficult to see what composes cooled volcanic rock, so the sample with a few visible crystals surrounded by a black, nondescript background would be the cooled rock from the molten river.
Answer to Question 2
Answer: Neptunists envisioned concentric shells of different types of rocks and minerals that precipitated in sequence from a primordial ocean solution that was extremely rich in dissolved materials. In his vision, the interior of the planet was cold, and volcanoes were rare, relatively recent phenomena related to the natural burning of subterranean coal beds. So, the bottom layer was believed to be thick, massive, mostly unlayered rocks, whose bottoms were never exposed to view, Primitive Rocks. These rocks formed, according to Neptunists, by precipitation and settling of the least-soluble silicate minerals before dry land appeared. The Primitive Rocks are overlain by the so-called Stratified Formations, distinctively layered rocks composed of precipitates of more-soluble minerals mixed in places with fragments worn from highlands of Primitive Rocks, which were gradually exposed as the enclosing ocean diminished in depth.
Atlatl mammoth ivory "creeping hyena", found in La Madeleine rock shelter, dated back to c
Rock and Plastic
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The rock cycle and the Earth’s physical environment
Surtsey, a volcanic island, during the time of its formation.