How water's properties change rock and land
Grade 9 Science Worksheet
Circle the best answer.
Read this first
Card (example data)
Site A: 120 days below 0 °C, 8 freeze-thaw cycles, 3 rockfalls a year. Site B: 60 days below 0 °C, 45 freeze-thaw cycles, 31 rockfalls a year. Both cliffs have water in their cracks.
Ari compares rockfall at two cliffs of the same granite (example data). Which explanation fits, and what should warming do at Site A?
- How cold it gets: A is colder, so warming will lower A's rockfall
- Frozen days: A has 120 against 60, so A's count must be a mistake
- Thawing ice shrinks and pulls cracks apart, so warming will not change A
- Freeze-thaw cycles, so warming that adds cycles at A raises its rockfall
Card (example data)
Crack width each spring: 1.0, 1.1, 1.3, 1.6 and 2.0 mm. Each winter the crack fills with water that freezes and thaws many times.
Bo measures one crack in a cliff each spring (example data). Which description of the trend and its cause fits best?
- It speeds up: a wider crack holds more water to wedge next winter
- It reverses: the crack narrows as ice contracts while freezing
- It is steady, about 0.25 mm a year, since each winter is the same
- It slows down as ice packs the crack and keeps more water out
Card (example data)
County A: heavy well pumping from 1990; water table fell 8 m; sinkholes per year 2 before 1990, 14 after. County B: little pumping; water table steady; sinkholes 2 before, 2 after.
Two counties sit on the same limestone and get the same rain (example data). Jun must say what raised sinkholes in County A. Which reading of the data is best?
- More rain dissolved A's limestone faster than B's after 1990
- Natural dissolving, since both counties sit on the same limestone
- New caves filled with stalactites and pressed A's ground down
- Pumping: A's sinkholes rose as its water table fell; B's did not
Card (example data)
Alpine site: water 3 °C, soil air 0.2% carbon dioxide, thin soil. Tropical site: water 25 °C, soil air 2% carbon dioxide, thick soil with roots and decay. Rain is equal.
Cold water holds more carbon dioxide than warm water, yet Kira finds tropical limestone dissolves faster than alpine limestone (example data). Which explanation fits the card?
- The data must be wrong, since cold water should dissolve more rock
- Heat itself dissolves limestone, so the warmer site must win
- Rain is equal at both sites, so the two rates should be the same
- Ten times the soil carbon dioxide outweighs cold water's solubility
Card (example data)
Winter cave air 600 ppm carbon dioxide, growth 0.12 mm a month. Summer cave air 3,000 ppm, growth 0.02 mm a month. Drip water is the same all year.
Luz logs a stalactite's growth and the cave air (example data). Why does it grow faster in winter?
- Winter rain is more acidic, so it carves the stalactite faster
- Cold slows chemistry, so winter growth ought to be the slower
- Low winter cave carbon dioxide lets drips degas and drop calcite
- Winter drips dissolve more calcite and so reshape the stalactite
Card (example data)
Reach A: discharge 50 m³/s, slope 0.002. Reach B: discharge 20 m³/s, slope 0.010. Reach C: discharge 100 m³/s, slope 0.0005.
Stream power grows with discharge × slope. In which reach does Milo expect the gravel bed to erode most (example data)?
- Reach C: it carries the most water, 100 m³/s
- Reach A: it is middling on both, so it balances out
- Reach C: its gentle slope slows the water so it scours
- Reach B: 20 × 0.010 = 0.20 is the largest product
Card (example data)
Before the dam, 1940–1969: sediment to the delta 12 million tonnes a year, shoreline steady, sea level rising 3 mm a year. After the dam, 1970–1999: sediment 1 million tonnes, shoreline retreating 20 m a year, sea level rising 3 mm a year.
The same river's delta is shrinking (example data). Pia must separate natural and human causes. Which conclusion do the records support best?
- Both causes equally, as each record changed by the same amount
- Sea-level rise: the sea kept rising, so the delta is drowning
- Sediment cut-off: retreat began when supply fell; sea-level rise held steady
- Stronger waves after 1970, as the sudden retreat itself shows
Card (example data)
Valley X: U-shaped cross-section, scratched bedrock, unsorted boulders and clay mixed together. Valley Y: V-shaped cross-section, rounded pebbles in sorted layers, a fast stream.
Ren surveys two valleys (example data). Which set of evidence best shows a glacier, not a river, carved Valley X?
- Steep valley walls with a stream on the valley floor
- U-shape, scratched bedrock, and boulders mixed with clay
- A deep valley lying far below the nearby ridge tops
- Rounded pebbles laid down in neat, sorted layers
Card (example data)
49 yearly peak flows; 1,200 m³/s ranks 5th. Recurrence interval T = (49 + 1) ÷ 5 = 10 years, a 10% chance each year.
A 49-year record ranks a 1,200 m³/s flood 5th. A builder says the site is safe for a 30-year home, as such floods come every 10 years and one just happened. Tala's verdict?
- About 10% risk overall, the same as for a single year
- Safe: one just happened, so the next is about 10 years off
- Unsafe: 10% each year makes about 96% over 30 years
- Certain: 30 ÷ 10 = 3 floods, which is a 300% chance
Card (example data)
Before levees, a 900 m³/s peak spread over the floodplain and gave a 4.0 m crest downstream. After levees, the same 900 m³/s peak gave a 5.2 m crest.
After levees were built upstream, the same peak discharge gives a crest 1.2 m higher downstream (example data). Which explanation does Zee choose?
- Levees made the river carry less water past the town downstream
- Levees kept flow off the floodplain, so it passed as a higher crest
- The levees slowed the water, so the river bed filled with sediment
- More rain must have fallen in the years after the levees went up