The Arizona STEM Acceleration Project
Seafloor Spreading
Seafloor Spreading
Evidence of Plate Tectonics
An 7th grade STEM lesson
Isiah M. Dalton
Date 6/2024
Examining isochron maps of the Earth's seafloor and looking for patterns to support evidence of continental drift. A prerequisite include a previous lesson of continental drift or students with some background of plate tectonics. This lesson is idea for 7th or 8th grade science students. Use the slides to introduce the lesson and present key content.
List of Materials
Arizona Department of Ed. Standards
Science 7.E1U1.6
Construct a model to explain how the distribution of fossils and rocks, continental shapes, and seafloor structures provides evidence of the past plate motions.
Math 7.RP.A.2 b.
Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships.
Technology 6-8.3.b. Students practice evaluating the accuracy, perspective, credibility, and relevance of information, media, data or other resources
ELA 7.L.6 Acquire and use accurate grades‐appropriate general academic and domain‐specific words and phrases; gather vocabulary knowledge when considering a word or phrase important to comprehension or expression.
Objective(s):
Agenda 50 Minutes
What is Seafloor Spreading
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other. Seafloor spreading and other tectonic activity processes are the result of mantle convection. Notice on the image the direction of the plates moving away from each other?
Mantle convection is the slow, churning motion of Earth’s mantle. Convection currents carry heat from the lower mantle and core to the lithosphere. Convection currents also “recycle” lithospheric materials back to the mantle.
source: National Geographic
How does Seafloor Mapping Help Us?
An isochron is a line on a map that connects points that have the same age.
An isochron map of the ocean floor supports the
theory of seafloor spreading because it shows the older rock near the deep sea trenches and the younger rocks near ocean ridges.
What features form at plate tectonic boundaries?
How are seafloor Isochron maps made?
Contemporary seafloor mapping is often conducted using multibeam sonar systems on ships and other marine vessels.
Multibeam systems produce high-resolution data, meaning that there are many data points per area. More data points means you can see more details.
Source: NOAA
Think Further
How do scientist use soundwaves or echos to map the seafloor?
What relationship does seafloor spreading have with isochron maps?
How does the theory of seafloor spreading support the theory of continental drift?
Assignment
Assessment
Differentiation
Look up a Google image diagram of seafloor spreading, Then draw a model of seafloor spreading. Label all the features at each point then on a separate sheet of paper write captions for all the underwater features.
Remediation
Extension/Enrichment
1. Seafloor Spreading Model Project
2 . Legend Of Learning Seafloor Spreading games
Account Required
3. CK 12 6.3 Seafloor Spreading