Plate Boundaries Worksheet
Name ___________________
The crust of the Earth is broken into plates which are on the move due to convection currents below in the Asthenosphere
layer of the Mantel. Plates that run into one another are called convergent. Plates that are spreading or moving away
from one another are called divergent. Plates that are sliding by one another are called transform. Your job is to use the
diagram below to complete the chart below on the different types of plate boundaries.
* Label the Boundary/Margin type for the
3 diagrams on the left.
* Draw some convection currents in the diagram above that would explain the hot spot and the divergent boundary.
Convergent
Motion (Describe the
motion of one plate
relative to another)
Effect (Is it constructive or
destructive to 1 or more
of the adjacent plates?)
Topography (What are
the landforms that are
associated with this type
of margin?)
Volcanic Activity?
(Yes/No)
Earthquake Activity?
(Yes/No)
Use your plate map to
identify 2 places in the
world with this type of
plate boundary/margin
Type of Margin/Boundary
Divergent
On land you see:
In the ocean you see:
Transform
Usually you don’t really
“see” a fault line at a
transform margin.
Sometimes you do.
Seafloor Spreading and Magnetic Reversals
Albert Einstein called the generation of Earth’s magnetic field one of the greatest mysteries in physics.
Scientists are still not sure how the field is generated, though it is clearly related to the movement of
molten iron in the liquid outer core. Even more puzzling is why the field switches back and forth between
normal and reversed polarity.
The measured strength of the magnetic field has dropped by 5-10% in the last 150 years, and less precise
readings suggest it may have weakened by 25-50% over the last 5,000 years. Satellites have detected
two areas in the mantle that appear to have reversed polarity. These data have led some to speculate that
a magnetic reversal may be imminent.
1. Based on the diagram, how many times has the Earth's magnetic field reversed during the past
four million years?
2. Approximately when did the current interval of normal polarity begin?
3. If there had been compasses four million years ago, which direction would compass needles have
pointed?
4. Why are the magnetic stripes on the sea floor parallel to and symmetrical across the mid-ocean
ridge?