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In the cold storage room at the USGS Pacific Coastal and Marine Science Center, we store cores on large racks that can hold about 4,500 full sized cores or D-tubes with split cores, up to 1.5 meters long.

The back door of the refrigerator connects to our core and sample processing labs.

Flowing groundwater site in Indiana

Our fume hood lab allows for sample preparation in safe conditions.

In the core lab, the Geotek core splitter cuts sediment cores in half lengthwise using oscillating saws and a wire cutter.

Ice Jam Webcam image of Mohawk River at Stockade bridge, Schenectady

Sunset view of the Kīlauea summit lava lake showing an active area of spattering at the right margin. Jagged openings between cooler crustal plates reveal molten lava. HVO is faintly visible on the Kīlauea Caldera rim at upper left. USGS photo February 13, 2017.

The Beckman Coulter LS 13 320 uses laser diffraction to automatically analyze sediment size fractions between 2 millimeters and 0.35 micron (-1 phi to 11.5 phi).

The first stop for many sediment cores is the Geotek MSCL or multi-sensor core logger. The logger automatically measures P-wave velocity, magnetic susceptibility, electrical resistivity, and gamma density at intervals from 1 millimeter to 1 centimeter along cores up to 1.5 meters long.

Lab technicians create written descriptions of sediment cores, referencing Munsell chart colors and standard phrases.

This is the Pacific Coastal and Marine Science Center's Sediment Prep Lab, where sediment samples and core subsamples are prepared for analyses.

We add about 20 grams of sediment from a sample to distilled water for particle size analysis. Then we add strong hydrogen peroxide to break down organic matter that makes clay particles stick together. Digestion takes place overnight.

We take most cores and samples straight from the loading dock into a large walk-in refrigerator (about 780 square feet), kept at the international core curation standard of 4° C plus or minus 2° C. Each core and sample must be labeled with an identifier and metadata, which follows the material through processing and analysis.

At the USGS Pacific Coastal and Marine Science Center, we have 3 WS Tyler RX-29 Ro-Taps that can dry-sieve coarser samples. This machine automatically rotates and taps the stack of sieves, so that smaller sediment falls through to the next sieve. Weighing the sediment trapped in each sieve gives us sediment size fractions.

These track-mounted racks pack together to save space. Cranking a handle moves the aisle between racks for core access.

We can use the tried-and-true method of washing samples through finer and finer sieves, then weighing the sediment trapped in each sieve, to determine sediment size fractions.

After adding a little sodium hexametaphosphate dispersant, we use a plunger to carefully stir the cylinder then let it settle, to ensure good mixing and standardized suspension of the sediment.

For some projects, scientists want to calculate sediment settling velocity and need to measure particle size using gravity. We use custom-built settling tubes filled with water – three at 2 meters tall (like the one shown here) and one 3 meters tall.

After releasing sediment into the top of a settling tube filled with water, a pan and microbalance collects and weighs the sediment as it slowly reaches the bottom of the tube. A computer records the cumulative sediment weight over time, as well as how long it took each particle to reach the pan.

The settling tube is filled with water and a pre-weighed sediment sample of mixed particle sizes is poured onto this brass "gate" at the top of the tube. When the operator flips the switch, the gate opens quickly like a venetian blind, releasing the whole sediment sample into the water column at the same time.

Washing a sediment sample through two sieves with distilled water lets us measure the fractions of gravel (bigger than 2 millimeters or -1 phi) and sand (2 millimeters to 63 microns, -1 phi to 4 phi). Smaller sediment passes through the sieves into a standard 1-liter graduated cylinder.