7.2-Development of a Theory

As new seafloor moves away from an ocean ridge, the seafloor cools and becomes less dense than the material beneath it. _______________

• true

• false

• both a & b

Seafloor spreading occurs because ____.

• new material is being added to the asthenosphere

• earthquakes break apart the ocean floor

• sediments accumulate at the area of spreading

• molten material beneath Earth's crust rises to the surface

Tags

NGSS.MS-ESS2-2

NGSS.MS-ESS2-3

The magnetic pattern of ocean-floor rocks on one side of an ocean ridge is ____.

• a mirror image of that of the other side

• younger than on the other side

• much different from the magnetic pattern found in rocks on land

• at right angles to the ocean ridge

The driving forces of tectonic plates are related to convection currents in Earth’s ____.

• crust

• mantle

• inner core

• outer core

Tags

NGSS.MS-ESS2-3

The alignment of iron minerals in rocks when they are formed reflects the fact that Earth's ____ has reversed itself several times in the past.

• magnetic field

• core

• asthenosphere

• gravity

Tags

NGSS.HS-PS2-5

Bands of rock on the seafloor showing alternating magnetic orientation indicate Earth's magnetic field has ____.

• reversed itself in the past

• weakened

• become stronger

• remained the same

While studying the ocean floor, scientists found ____ bands of magnetism.

• plastic

• alternating

• no

• rectangular

Tags

NGSS.MS-ESS2-3

A vast, underwater mountain chain is called a(n) _________.

• deep-sea trench

• oceanic crust

• ocean floor sediment

The youngest rocks on the ocean floor are located ____.

• near continents

• at mid-ocean ridges

• far from mid-ocean ridges

• near Asia

Tags

NGSS.MS-ESS2-3

The youngest part of the ocean floor is found ____.

• along deep sea trenches

• where ocean sediments are thickest

• near ocean ridges

• where Earth’s magnetic field changes polarity