USGS

What can something smaller than a grain of sand reveal about Earth's past?

Meet pollen and spores, tough little grains built to survive. These microscopic structures are produced by plants as part of their reproductive cycle. Once they are dispersed by wind, insects, or other means, they can settle into sediments and remain preserved for thousands or even millions of years. The oldest known land plant spores date back about 480 million years, and pollen from flowering plants has been found in rocks at least 125 million years old.

So how does pollen help us understand climate?

Because plant distribution is shaped by temperature, moisture, and other environmental conditions, the pollen preserved in a layer of sediment acts like a snapshot of the vegetation (and climate) that existed when it was deposited. Scientists study these fossil grains to reconstruct patterns of past vegetation and piece together how climate has shifted over time.

These records, combined with modern measurements, show past climate conditions across timescales, from year-to-year variation to fluctuations spanning millions of years. USGS paleoclimate scientists use evidence from pollen, ice cores, tree rings, marine microfossils, corals, and isotopes to characterize past environmental conditions, helping researchers improve climate models, predict changes in the water cycle, and anticipate future shifts in El Niño and La Niña patterns.

This understanding of ancient climate also informs real-world decisions, from assessing how sea level rise might affect coastal fishing industries to evaluating how shifting vegetation could shape future agriculture.

📷: Pollen and spores preserved in sediments. Credit: USGS

#paleoclimatology

Meet Annautaq, an orphaned Pacific walrus calf whose unexpected discovery during USGS research in Alaska saved his life.

Last month, USGS biologist Tony Fischbach and Violet Anniskett, an Illisavik College intern, were surveying a beach after a storm moved a walrus herd from the area. While sampling carcasses for a study on harmful algal toxin levels in Pacific walruses, Violet discovered a live, orphaned calf hiding between two adult carcasses.

With approval from the U.S. Fish and Wildlife Service (USFWS) and the local Iñupiaq community, the pair cared for the calf for nearly four days. They dispersed the gulls scavenging him, walked a half mile to the nearest shelter (an abandoned building open to the elements), and protected him from polar bears until the storm passed and a local rescue team could boat him across the lagoon. From there, Alaska Sea Life Center (ASLC) vet techs crated him onto a small plane to rehabilitation. Violet joined the journey to ease his transition.

Violet grew up near walrus herds and first joined USGS surveys on a high school class field trip. This September, she joined the USGS team to gain professional experience working with the wildlife central to Iñupiaq culture. Her community agreed to have the orphan saved with the condition that they name him to preserve their connection to him. Violet chose Annautaq, an Iñupiaq word meaning axe, in honor of her father’s Iñupiaq name.

USGS scientists monitor Pacific walrus populations in support of Marine Mammal Protection Act reporting and management requirements. This work depends on partnerships with Alaska Native communities, whose generational knowledge shapes how we understand and protect these animals.

After rehabilitation at the ASFC, Annautaq has moved to his long-term home, where he will serve as a species ambassador, helping people learn about walruses and their connection to Alaska's people and changing marine environments.

All work was conducted under USFWS permit MA3376D.

📷1: Violet and Annautaq.
📷2: Annautaq gazes out the shelter window.
📷3: Tony and Annautaq.
📷4: Violet resting with Annautaq.

Credit: Tony Fischbach, USGS

What can lava samples tell us about Kīlauea’s recent summit lava fountains? 🌋

Since the current eruption began in late 2024, scientists with our USGS Hawaiian Volcano Observatory have analyzed 178 lava samples from episodes 1–39 to better understand the magma feeding the eruption and changes occurring beneath the surface.

Here’s what they found:

💠 Variations in fountain height and episode duration are not associated with significant compositional changes

💠 The eruption is fed by lava from the magma chamber that is about a mile (1–2 km) beneath Halemaʻumaʻu

💠 There is evidence that the parts of former lava lake eruptions in Halemaʻumaʻu (between 2020–2023) remain molten below the surface and sometimes influence the chemistry of material erupted by lava fountaining

💠 A subtle change in chemistry suggests that a new magma was erupted within a few weeks of the eruption onset

💠 Kīlauea’s shallow magma storage system beneath Halemaʻumaʻu showed an increase in temperature through fountaining episodes 1–39

Together, these findings offer new clues about the magma system driving Kīlauea’s ongoing eruption.

Read the full article: ow.ly/QTKB5101RA0

📷1-2: A scientist collecting fresh lava samples from the Kilauea.
📷3: Analyzing lava samples in the lab.
📷4: An annotated image of a lava sample under a microscope.

@USGSVolcanoes

500 million years of Earth’s history are written in the rocks of the Sierra Nevada. 🗺️⛰️

The Sierra Nevada is one of the most iconic landscapes in the western U.S., a major mountain range stretching north to south along eastern California and into a small portion of western Nevada. Its rocks hold a story that spans more than 500 million years.

Now, the Sierra Nevada Earth Science Atlas brings that story into sharper focus.

Created through a collaboration between the @CAGeoSurvey and the USGS, the Atlas provides the most detailed geologic framework of the Sierra Nevada to date. Why does that matter? Detailed geologic maps help scientists and resource managers understand what lies beneath the surface, from the rocks and faults that shape the landscape to the mineral resources and geologic processes that affect the region.

From ancient ocean deposits and volcanic islands to massive mountain-building events, erosion and glaciation, the Atlas captures the geologic processes that shaped the Sierra Nevada we see today.

This initial release features a geologic map and descriptive text, with more components of the full Atlas coming soon. Upcoming map layers will depict carbonate rocks, fossils, metallic mineralization regions, and geochronology data, along with an associated report.

Explore the Atlas 👉 ow.ly/HXwc5101rgf

📽️ Video consisting of several clips of the Sierra Nevada Earth Science Atlas. The video pans and zooms across the map to show different geographic and geologic features. The video includes close-up views of map details, the legend, and the entire atlas.

Ready to go batty? 🦇 Celebrate Bat Week with a few fun facts about these nighttime flyers!

🦇 Bats eat – a lot! A single little brown bat, which has a body no bigger than an adult human’s thumb, can eat 4 to 8 grams (the weight of about a grape or two) of insects each night. Others feed on feed on fruit, nectar, or pollen.
🦇 Bats are not blind. They have small eyes with very sensitive vision, which helps them see in conditions we might consider pitch black.
🦇Bats are important pollinators. More than 300 species of fruits and plants rely on bats for pollination and seed dispersal. Bats are significant pollinators to cacao, the key ingredient in chocolate.
🦇Not all bats hibernate. In winter, bats either hibernate or migrate to warmer areas. One hoary bat GPS tagged by USGS scientists traveled from Marin County, California to southwest Idaho!
🦇 Bats make up one-fifth of all mammalian species worldwide and are found on every continent except Antarctica.

📷1: ‘ōpe‘ape‘a (Hawaiian hoary bat) - The only land mammal native to the Hawaiian archipelago that still exists today. They prefer coastal lowlands during breeding season (May to October) and move to interior highlands in winter. They feed on insects and roost in trees. Credit: USGS

📷2: Spotted Bat – One of the few bat species whose echolocation frequency is low enough for humans to hear. Little is known about this species, but it is believed to roost in high cliff crevices and feed primarily on moths. Credit: USGS

📷3: Cave myotis - Found throughout the southwestern U.S., they feed on insects and form nursery colonies, usually numbering in the thousands, in caves, mines, barns, buildings, and sometimes under bridges. Credit: J Scott Altenbach, NABat

📷4: Indiana Bat - This small, insectivorous, migratory bat requires forests for foraging and roosting. They are found in forested areas in the eastern U.S. and hibernate in colonies in caves and mines in the winter. Credit: Dane Smith, NABat

#BatWeek