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?

   • A, where the water is fastest
   • Nowhere; the river keeps them moving to the sea
   • 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?

   • Y, on the inside bend, where water is slow
   • X, on the outside bend, where water is fast
   • X, because erosion piles sand up
   • Both banks equally
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 5,000 years
   • One big flood, over a few days
   • About 5 to 6 million years
4. 4.

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

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

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

   • Neither; this is deposition
   • Both, since both weathered the same way
   • Rock B, since its color changed
   • 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 water dissolves the rock into a new mineral
   • Nothing; ice is softer than rock
   • Freezing water pushes it wider, bit by bit
   • The ice carries the rock downhill right away
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?

   • River carries pieces, ice cracks cliff, river drops sand
   • Ice cracks cliff, river drops sand, river carries pieces
   • Ice cracks cliff, river carries pieces, river drops sand
   • River drops sand, river carries pieces, ice cracks cliff
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
   • Both seasons: weathering
   • Storms: erosion; calm weather: deposition
   • Storms: weathering; calm weather: erosion
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?

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