Question

draw a sedimentary rock before and after weathering:
before:
after:
why?
draw an igneous rock before and after weathering:
before:
after:
why?

Explanation:

Sedimentary Rock:

• Before Weathering: Sedimentary rocks form from compacted/cemented sediments, so they have distinct layered (stratified) structures, smooth or slightly rough intact surfaces, and sharp edges.
• After Weathering: Water, wind, and biological processes break down the cement holding sediments together. The rock splits along layers, edges erode into rounded shapes, and small sediment fragments separate from the main rock.
• Why?: Sedimentary rocks have weak cement between sediment grains and layered structures, making them prone to erosion along these weak points; weathering agents target these gaps to break the rock apart.

Igneous Rock:

• Before Weathering: Igneous rocks form from cooled magma/lava, so they have a crystalline (interlocking mineral) structure, no layers, and hard, solid, sharp-edged surfaces (e.g., granite with visible quartz/feldspar crystals).
• After Weathering: Chemical weathering breaks down minerals (e.g., feldspar turns to clay), and physical weathering chips at the surface. The rock develops pitted, rough surfaces, edges round off, and small mineral grains flake off, but it remains more intact than weathered sedimentary rock initially.
• Why?: Igneous rocks have a dense, interlocking mineral structure that is harder than sedimentary rock cement, so they resist weathering longer, but mineral-specific chemical breakdown and physical abrasion still alter their form over time.

Answer:

Sedimentary Rock

• Before: A solid, rectangular rock with clear horizontal layers, sharp corners, and a smooth surface.
• After: A fragmented rock with broken, rounded edges, separated small sediment pieces, and eroded, uneven layer surfaces.
• Why?: Weak sediment cement and layered structure make it easy for weathering agents to break apart the rock along layer gaps and loosen individual sediment grains.

Igneous Rock

• Before: A solid, blocky rock with visible interlocking mineral crystals, no layers, and sharp, angular edges (e.g., a piece of granite).
• After: A rock with pitted, rough surfaces, rounded edges, and small mineral flakes chipped off; the main rock mass remains mostly intact.
• Why?: Its dense, interlocking crystalline structure is harder, so it resists weathering better than sedimentary rock, but chemical breakdown of minerals and physical abrasion still wear down its surface and edges over time.