Brendan-Science Flashcards
According to the _____________, the forces that are changing Earth’s surface today are the same forces that changed Earth’s surface in the past.
principle of uniformitarianism
In undeformed rock layers, the youngest layer is on the top and the oldest layer is on the bottom, according to the ____________.
law of superposition
____, ______, and ______ are interruptions in the sequence of rock layers and are collectively know as unconformities.
nonconformities angular conformities and disconformities
According to the ________, a geologic feature is always younger than the rock it cuts through.
law of crosscutting relationships
Because rates of erosion and deposition can change over time, they are imprecise methods for determining .___________________.
absolute ages of rocks
_____________are layers of sediment that form in glacial lakes as a result of the annual cycle of freezing and thawing of the glacier.
varves
Radioactive elements decay at constant and measurable rates and can be used to determine _______________ .
absolute age
___________ may be preserved in amber, in tar seeps, or through freezing or mummification.
Entire organisms
Fossilized evidence of organisms includes _______________________.
trace fossils, carbon films, molds, casts, coprolites, and gastroliths.
Index fossils occur only in rock layers of a particular ____________ , and they can help geologists estimate the age of rock formations.
geologic age
-Fossil, rock, and climatic evidence supports ________________. However, Wegener could not explain the mechanism by which the continents move.
Wegener’s hypothesis of continental drift.
New ocean floor is constantly being produced through sea-floor spreading, which creates_____________ and changes the topography of the sea floor.
mid-ocean ridges
The ________________ of the rock of the ocean floor show that new lithosphere forms at a mid-ocean ridge and then moves away.
magnetic properties
_____________ provides evidence that tectonic plates move and change.
Sea-floor spreading
The theory of ______________proposes that changes in Earth’s crust are caused by the very slow movement of large tectonic plates.
plate tectonics
