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Earth and Space Science

Unit 1

Earth as a System

6 topics · 24 practice questions · Free responseNot yet reviewed

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Notes

Earth science and the spheres

  • Earth science uses the scientific method: testable hypotheses, data and conclusions. A theory is a well-tested explanation.
  • Earth has four interacting spheres: geosphere, hydrosphere, atmosphere and biosphere.
  • Earth is an open system for energy (the Sun is the main source) and nearly closed for matter. Feedback loops amplify (positive) or reduce (negative) change.

Location and maps

  • Latitude is measured north or south of the equator (0° to 90°). Longitude is measured east or west of the prime meridian (0° to 180°).
  • Earth rotates 15° per hour, so 15° of longitude equals 1 hour.
  • Map scale converts map distance to real distance. All flat maps distort Earth.

Topographic maps

  • Contour lines join equal elevations. Close lines mean steep slopes; wide spacing means gentle slopes.
  • Relief equals highest minus lowest elevation. The contour interval is the elevation change between lines.

Topics in this unit

Each topic has its own short notes and practice.

Practice

Which of these is part of the hydrosphere?
A city is at 45° N, 90° W. This means it is:
Two cities differ by 75° of longitude. Their local solar times differ by:
On a map with scale 1 cm = 20 km, a lake is 3.5 cm wide. Its real width is:
Which is the best example of a positive feedback loop?
On a topographic map, a stream crosses contour lines forming V shapes. The V points:

Free response

Write your answer first, then open the scoring guide.

Free-response question

A hiker studies a topographic map with a contour interval of 20 m. The map scale is 1 cm = 500 m. A summit is labeled 1,460 m and the lake at the base of the trail is at 1,220 m. The summit and lake are 6 cm apart on the map.

(a) Calculate the relief between the summit and the lake.

Show the answer and scoring guide

$1460 - 1220 = 240$ m.

Check off the points you earned:

(b) Calculate the real horizontal distance between them in kilometers.

Show the answer and scoring guide

$6 \times 500 = 3000$ m, which is 3 km.

Check off the points you earned:

(c) How many contour lines (at 20 m intervals) lie between the lake and the summit, and what would closely spaced lines near the summit show?

Show the answer and scoring guide

$240 \div 20 = 12$ intervals, so about 11 lines lie between them (the endpoints are at 1,220 and 1,460). Closely spaced lines near the summit would show a steep slope.

Check off the points you earned: