Boundstone
“Reef rock built by living organisms”
Boundstone is a limestone formed by organisms that build rigid frameworks — corals, sponges, bryozoans, and algae that grow in place and bind sediment together. Ancient boundstones record the history of reef ecosystems stretching back hundreds of millions of years.
calcite, aragonite, fossil coral/sponge/algae frameworks, calcite cement, micrite
Great Barrier Reef (Australia — modern), Permian Reef Complex (Texas, USA), Dolomites (Italy), Gotland (Sweden)
3-4
The Permian-age reef complex at Guadalupe Mountains National Park in Texas is one of the best-preserved ancient reefs on Earth — it was built 265 million years ago by sponges and algae, not corals.
Test Your Knowledge
Why was the Permian reef at Guadalupe Mountains built by sponges and algae rather than corals?
Photo Attribution
Related Specimens
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