The tree rings of 52 fallen giant sequoias, Earth's biggest trees, have revealed a 3,000-year-old history of droughts and fires. Hemera/ThinkStock ...

The massive, resilient trees are showing increased signs of stress amid California's historic drought, now in its fourth year, researchers said.

A segment of a giant sequoia tree was moved on Friday from the Arizona State Museum South building to the Bryant Bannister Tree-Ring building, which is currently under construction.

Look at this photo of a section of rings from a giant sequoia tree trunk and click on the area you think might represent a very wet season ...

Scientists reconstructed the 3,000-year history of fire by dating fire scars on ancient giant sequoia trees, Sequoiadendron giganteum, in the Giant Forest of Sequoia National Park.

A 16 Million Year Old Tree The world-famous museum is now in the possession of an ancient slab of a sequoia tree. After carefully counting each ring of the tree, paleobotanist Scott Wing ...

Known as the General Sherman tree, the tree was first estimated at nearly 6, 000 years years old, while more recent estimates in the 1960s cut its age to 3, 500 years and even to 2,500 years.

The sequoia section arrived at the UA in 1931 for study by astronomer A.E. Douglass, who later founded the world's first tree-ring research laboratory underneath the Arizona Stadium.

Rome Free Academy science teacher Elaine Rotenberry, left, and reading teacher Melinda Boufford planted Arti, a giant sequoia sapling in May.

A cutaway piece of a 1,000-plus year-old giant sequoia tree from Kings Canyon National Park in eastern Fresno County has arrows on its rings to show where fire burned the tree about every 12 years ...

Given that the sequoia grew seasonally, each ring marks the passage of another year, and visitors can look at the approximately 260 delineations and think about what such a time span represents.