Relationships Between... Flashcards
Loss of Banded Iron Formations and Redbeds:
The disappearance of banded iron formations and the appearance of redbeds suggests that atmospheric oxygen had reached a moderate level early in Proterozoic time. Before this, oxygen was scarce.
Chlorophyll and atmosphere:
Chlorophyll (found in chloroplast) absorbs light and is responsible for photosynthesis. The atmosphere uses this oxygen from the chlorophyll.
Heat flow and greenstone belts:
High heat flow means that continental plates were moving rapidly. The converging continents creates subduction zones where greenstone belts are formed (from sediments, oceanic crust, and arc volcanics along the margins). They formed from high heat and pressure and sit atop felsic metamorphic rocks.
Mesosaurus and Gondwanaland:
Mesosaurus, a small Early Permian reptile, was found in both South Aftrica and southern Brazil. This helped lead to the theory that Gondwanaland was one connected “supercontinent” connected by landmasses.
Coccolithophores and the Cliff’s of Dover:
The Cliff’s of Dover are composed of coccolithophores (components in chalk), which are one-celled organisms that live in large populations in the ocean. They surround themselves with calcite.
Birds and Dinosaurs:
Birds and dinosaurs both lay eggs in a nest, have very similar bone structures, and some dinosaurs had feathered wings and could fly. It can be hypothesized that dinosaurs evolved into birds.
Glossopteris flora and the theory of plate tectonics:
Glossopteris flora were found on many different (presently disconnected) continents. This gives evidence that landmasses once connected all the continents.
Ring of Fire and subduction zones:
The Ring of Fire is a series of volcanoes. Volcanoes often occur at subduction zones on plate boundaries, so The Ring of Fire shows where the subduction zones are.
Ophiolite suite and subduction zones:
Ophiolite suites occur when a plate is subducted below another plate on a peripheral margin. They are key in recognizing plate convergence along subduction zones.
Detrital uraninite and pyrite and the composition of the early atmosphere:
Detrital uraninite and pyrite oxidize very easily. Early rocks containing these minerals, however, show that they had not been oxidized. This leads us to believe that earth’s early atmosphere lacked oxygen.
Neoteny and human evolution:
Neoteny is when adult species retain child-like appearances. Humans show this because they don’t go through “metamorphasis” like apes do. Humans are the neotonous ape.
