Weathering, erosion and deposition: how land is worn down and built up

Grade 6 Science Worksheet

Circle the best answer.

1. 1.

   Bo's diagram shows a river running from a steep mountain into a still lake. Where does the river drop its biggest pebbles first?

   • Nowhere; the river keeps them moving to the sea
   • A, where the water is fastest
   • B, where the river first slows down
   • C, in the still lake, at the very end
2. 2.

   Jun's map shows a river bend. Water flows fastest along the outside bank, X, and slowest along the inside bank, Y. Where does sand pile up into a sandbar?

   • Both banks equally
   • X, because erosion piles sand up
   • X, on the outside bend, where water is fast
   • Y, on the inside bend, where water is slow
3. 3.

   Luz reads that the Colorado River carved the Grand Canyon. About how long did that take, according to the National Park Service?

   • About 50 years
   • About 5 to 6 million years
   • One big flood, over a few days
   • About 5,000 years
4. 4.

   Milo sorts changes to the land into fast and slow. Which change usually happens fast?

   • A river carving a canyon
   • Rain dissolving a limestone cave
   • A glacier carving a valley
   • A flash flood moving boulders in an afternoon
5. 5.

   Noah visits a limestone cave. Rainwater carrying a weak acid seeped through the rock for ages and dissolved it. Which process made the hollow space?

   • Chemical weathering, dissolving the limestone
   • Mechanical weathering by ice
   • Erosion by wind
   • Deposition of new rock
6. 6.

   Rock A cracked into sharp pieces of the same gray stone. Rock B turned rusty and crumbly. Which shows mechanical weathering, by Pia's clues?

   • Both, since both weathered the same way
   • Rock B, since its color changed
   • Neither; this is deposition
   • Rock A, broken but still the same stone
7. 7.

   Water expands by about 9% when it freezes. Ren reads about a rock crack that fills with water and freezes each winter night. What happens to the crack?

   • The ice carries the rock downhill right away
   • Nothing; ice is softer than rock
   • The water dissolves the rock into a new mineral
   • Freezing water pushes it wider, bit by bit
8. 8.

   “in jumbled order” Three events: a river drops sand in a lake, ice cracks a cliff, and the river carries the pieces. Which order does Tala choose?

   • Ice cracks cliff, river drops sand, river carries pieces
   • River drops sand, river carries pieces, ice cracks cliff
   • River carries pieces, ice cracks cliff, river drops sand
   • Ice cracks cliff, river carries pieces, river drops sand
9. 9.

   A beach loses sand in winter storms and slowly gains it back in calm weather. Which pair names the two processes, says Zee?

   • Storms: deposition; calm weather: erosion
   • Storms: erosion; calm weather: deposition
   • Storms: weathering; calm weather: erosion
   • Both seasons: weathering
10. 10.

    A muddy stream flows into a quiet pond, and by the next day the pond water is clear. What happened to the mud, by Ari's thinking?

    • The stream's fast water kept it moving through
    • It dissolved and vanished
    • It was weathered into nothing
    • It settled to the bottom as the water slowed