Weathering, Erosion and How Soil Forms · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

From solid rock to living soil

Science · Earth's Systems · ages 14-15
Name ______________________   Date ____________

  1. Faintly sour rain dissolves limestone. What changed?

    • The rock place on the hill
    • The rock minerals themselves
    • The rock temperature only

  2. Ice freezes in a crack and wedges it wider. What kind of weathering is this?

    • Physical weathering
    • Chemical weathering
    • Erosion by ice

  3. Erosion is the movement of broken rock pieces to a new place.

    Circle one:   True   False

  4. A soil slice shows a pale layer full of clay between a dark top and broken rock. Which layer is it?

    • The dark top layer
    • The middle accumulation layer
    • The solid bedrock

  5. A student says cracked rock rots faster in sour rain. Why is that right?

    • Cracks give chemistry more surface to attack
    • Cracks keep the rain off the minerals
    • Cracks freeze the rock solid

  6. Warm wet climates usually build deeper soils than cold dry ones.

    Circle one:   True   False

  7. A farmer wants the richest ground for roots. Where should she dig her beds?

    • Into the solid bedrock
    • Into the pale middle layer
    • Into the dark top layer

  8. The same rock forms deep soil in one valley and bare slabs in another. What best explains it?

    • Wetter, warmer weather on the deep soil side
    • Stronger gravity pulling soil off the bare rock
    • Louder winds naming the valleys differently
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Answer key

For grown-ups. Fold this page away before handing over the rest.

From solid rock to living soil W1-mt_nQOPOt1VTH-s1

  1. The rock minerals themselves · Dissolving limestone changes the minerals. That is chemical weathering.
  2. Physical weathering · Cracking without changing the makeup is physical weathering. Nothing moved away.
  3. True · Breaking down is weathering. Carrying pieces to a new place is erosion.
  4. The middle accumulation layer · Clay washed down from above collects in the middle layer, between topsoil and broken rock.
  5. Cracks give chemistry more surface to attack · More surface means more room for chemistry to bite, so cracked rock rots faster.
  6. True · Warm wet weather rots rock fast and grows plenty of life, building deep soil.
  7. Into the dark top layer · Roots live where rotted life meets weathered grit: the dark top layer.
  8. Wetter, warmer weather on the deep soil side · Same rock rules out recipe. Different weather explains different depths.
Worksheet · LightMySky