Desert Varnish Quiz: Dark Rock Coatings and Petroglyphs
This desert varnish quiz runs a finger over the dark, shiny skin on desert cliffs. Play 10 interactive questions on coatings of manganese and iron oxides mixed with clay, growth so slow it takes thousands of years, the possible role of microbes, petroglyphs carved by scraping through to lighter rock, Newspaper Rock in Utah and how varnish helps estimate ages.
Start Desert Varnish Quiz
🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds
What
What is desert varnish?
Made
What is desert varnish mainly made of?
Where
Where does desert varnish form?
Speed
How fast does desert varnish form?
Microbes
What may help make desert varnish?
Color
What colors can desert varnish be?
Art
How were many petroglyphs made?
Utah
Which Utah rock panel is covered in petroglyphs?
Age
How can varnish help archaeologists?
Protect
Why should visitors not touch petroglyphs?
Your score
0/10
Scroll down to see the explanation for each question.
Explanations: answer key for all 10 questions
- Q1: What is desert varnish?
Answer: A thin dark coating on desert rocks
It can look glossy.
- Q2: What is desert varnish mainly made of?
Answer: Manganese and iron oxides with clay
Dust supplies the clay.
- Q3: Where does desert varnish form?
Answer: On rocks in dry regions
Rain is scarce.
- Q4: How fast does desert varnish form?
Answer: Extremely slowly, over thousands of years
Layers are microscopically thin.
- Q5: What may help make desert varnish?
Answer: Microbes concentrating manganese
Research continues.
- Q6: What colors can desert varnish be?
Answer: Dark brown to black, or orange
Manganese makes it dark.
- Q7: How were many petroglyphs made?
Answer: By scraping through the varnish to lighter rock
The contrast shows the image.
- Q8: Which Utah rock panel is covered in petroglyphs?
Answer: Newspaper Rock
It holds hundreds of figures.
- Q9: How can varnish help archaeologists?
Answer: Regrowth over carvings hints at age
Older carvings are darker.
- Q10: Why should visitors not touch petroglyphs?
Answer: Oils and rubbing damage them
Varnish cannot quickly regrow.
The Dark Skin of Desert Rocks
Desert varnish is a thin dark coating that forms on rocks in dry regions. It is made mostly of manganese and iron oxides mixed with clay from wind-blown dust. Manganese-rich varnish looks dark brown to black, while iron-rich varnish can look orange.
Desert varnish forms extremely slowly, building microscopically thin layers over thousands of years. Microbes may help by concentrating manganese, though scientists are still studying how it forms.
Ancient peoples made petroglyphs by scraping or pecking through the dark varnish to reveal lighter rock below. Newspaper Rock in Utah holds hundreds of figures. Varnish slowly regrows over carvings, so older images look darker, a clue to their age. Visitors should not touch petroglyphs, since oils and rubbing damage them.
What This Quiz Teaches
Geology and history fans will enjoy these questions.
- What desert varnish is
- What it is made of
- How fast it forms
- How petroglyphs were made
- How it hints at age
Did You Know?
- Varnish streaks run down cliff faces.
- Rain washes over certain surfaces.
- Similar coatings are studied on Mars.
- Some panels show animals and hunters.
- Cracks in rock can host varnish too.
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