Clues In The Crust
In an undisturbed vertical cliff of sedimentary rock with four horizontal layers, this specific layer contains the oldest fossils
What is the bottom layer?
(By the Law of Superposition, older sediments settle first at the bottom
At the Mid-Atlantic Ridge, this molten material rises up from the mantle, cools, and hardens into brand new ocean floor
What is magma (or molten rock)?
Two plates sliding horizontally past each other form this boundary type, resulting in fault lines and frequent earthquakes like California's San Andreas Fault
What is a transform boundary?
As human populations in a region grow and demand more freshwater, this is the direct consequence for local wildlife
What is wildlife losing in competition with humans for water?
When excess nutrients from fertilizer runoff wash into coastal waters, surface algae feeds on the nutrients and creates this rapid green overgrowth
What is an algae (algal) bloom?
Finding thick, flat layers of limestone made from marine shells far inland in the central United States provides evidence for this historical condition
What is the area being covered by an ancient ocean over millions of years?
Comparing ocean crust near the Mid-Atlantic Ridge to ocean crust near the coastlines of South America and Africa, the youngest, most recently formed rock is located here
What is closest to the Mid-Atlantic Ridge?
Plates colliding and pushing toward each other create subduction zones, trenches, and volcanic chains around this vast Pacific perimeter
What is a convergent boundary (and the Pacific Ring of Fire)?
Over-pumping wells faster than rain can replenish them depletes these underground water-bearing rock layers
What are aquifers?
A dense mat of algae floating on the water's surface (green blanket) harms aquatic plants primarily by blocking this essential resource
What is sunlight?
Fossils and distinct horizontal strata are typically preserved in this major class of rock
What is sedimentary rock?
As continental plates pull apart and separate over millions of years underwater, this large sunken geographic feature forms between them
What is an ocean basin?
Plates dividing and pulling away from each other along the Mid-Atlantic Ridge represent this boundary type
What is a divergent boundary?
Household chemicals poured down drains and deicing salts or pesticides washed off roads and lawns can contaminate water.
What is pollution? (point-source or nonpoint-source pollution).
When algae blooms die, decomposing bacteria multiply and deplete this critical substance from the water
What is oxygen?
Marine limestone layers found across central Texas prove that large-scale geological deposition requires this timescale, rather than a rapid single-day flash flood
What are millions of years (deep geologic time)?
Discovering matching fossils, identical rock chemistry, and the exact same magma source in both West Texas and eastern Antarctica supports this major geological theory
What is the Theory of Plate Tectonics (or Continental Drift / Pangaea)?
Unlike volcanic arcs formed at plate boundaries, the Hawaiian Island chain formed because magma rose through the crust at this isolated thermal feature
What is a mantle hotspot?
These regular inspections help prevent leaks from contaminating groundwater and protect our water supply. Is this a harmful or beneficial human activity?
What is a beneficial activity?
When rain washes over suburban lawns and agricultural farms, this substance introduces massive amounts of excess nitrogen and phosphorus into local rivers and coastal bays.
What is fertilizer (or chemical fertilizer runoff)?
Name the geological process that forms brand-new oceanic crust where tectonic plates pull apart at underwater ridges,
What is Seafloor Spreading?
As newly solidified crust forms at underwater ridges, this happens to the older oceanic crust on either side
What is moving farther away from the ridge?
This is an event that occurs at all plate boundary types.
What are earthquakes?
Farmers use water-conserving technologies, such as efficient irrigation systems, to reduce freshwater use and protect water supplies.
What is a beneficial activity?
Ocean dead zones cause massive fish kills and force bottom-dwelling crabs and shrimp to flee, which heavily damages this coastal human industry and causes marine ecosystem stability to do this.
What is commercial fishing, and the ecosystem becomes LESS stable? (Losing biodiversity and food web links destabilizes the ecosystem).