Core locations, segment depths, and estimated compaction from vibracores collected in Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California

Cores were collected from the USGS coring platform Hadai. Water depth was measured using a reel tape measure with a weighted disc to determine the sediment surface. A handheld global satellite navigation system (GNSS) receiver was used to determine the locations of sediment samples. Lake sediment was collected in approximately 6-meter-long aluminum irrigation pipes with an outer diameter of 76.2 mm and a wall width of 1.27 mm. Pipes were coupled using aluminum sleeves, and a Honda GX160 5-horsepower 4-stroke motor drove a concrete vibrator head at approximately 167 Hz, which was clamped to the pipes. Brass-fingered core-catchers were used to prevent loss of sediment out the bottom of the pipes during extraction. Cores were segmented into 150 cm or shorter lengths. The top and bottom depths of each core segment are reported in centimeters below the lakebed. Due to significant sediment compaction while coring, the sediments originally at the lakebed surface (0 cm) were driven down to 289 cm in VC01A and 158.5 cm in VC01B. The upper sediment layers in these cores are compacted more than the sediment layers near the bottom, around 11 meters below the lakebed, thus the grains of sediment near the bottom of the core are closer to their true depths before being disturbed by coring. The core depths in the other datasets of this data release report uncorrected depths, thus the uppermost core segments start at 158.5 and 289 cm, even though the sediment at the top of these core segments represent the lakebed surface (0 cm) on October 29, 2018. Associated publications may use depths that are corrected to 0 cm at the top. The comma-separated values (csv) file in this dataset provides both the original and the corrected upper depths for each segment. Compaction percentages were calculated in the field after driving the vibracores to refusal, but before extraction, by dividing the distance from the lakebed surface to the top of the sediment in the pipe within the core by the total drive (distance below the lakebed that the core string was driven). The compaction was 15 percent and 24 percent for VC01A and VC01B, respectively. Core depths and water depths were not associated with a fixed vertical datum at the time of core collection. Cores were segmented into 150 cm (or shorter) sections in the field and split into "working" and "archive" halves in the lab.