Stable isotope evidence for long-term stability of large-scale hydroclimate in the Neogene North American Great Plains

The Great Plains of North America host a stark climatic gradient, separating the humid and well-watered eastern US from the semi-arid and arid western US, and this gradient shapes the region’s water availability, its ecosystems, and its economies. This climatic boundary is largely set by the influence of two competing atmospheric circulation systems that meet over the Great Plains—the wintertime westerlies bring dominantly dry air that gives way to moist, southerly air transported by the Great Plains Low-Level Jet in the warmer months. Climate model simulations suggest that, as CO2 rises, this low- level jet will strengthen, leading to greater precipitation in the spring, but less in the summer and, thus, no change in mean annual precipitation. Combined with rising temperatures that will increase potential evapotranspiration, semi-arid conditions will shift eastward, with potentially large consequences for the ecosystems and inhabitants of the Great Plains. We examine how hydroclimate i..., , , # Stable isotope evidence for long-term stability of large-scale hydroclimate in the Neogene North American Great Plains

Table S1-Ogallala formation authigenic carbonate stable isotope data

[https://doi.org/10.5061/dryad.5hqbzkhc5](https://doi.org/10.5061/dryad.5hqbzkhc5)

This dataset provides all of the carbonate stable isotope data referenced in the study. Please see the associated manuscript for sampling and analytical methods.

## Description of the data and file structure

The data in this Table is organized by stratigraphic section. The first tab is a Metadata tab that lists all of the stratigraphic section, their short abbreviation, and the latitude and longitude. Also listed is the paper(s) which first studied the section and provided an age estimate.

In each tab (organized alphabetically), there are sixteen columns:
Section ID: The two-four letter/number abbreviation for the section.
Sample ID: The letter or number combination assigned to each unique sample.
Longitude (°E):...