What is Loess?
Loess (pronounced "luss") is fine, wind-blown silt that accumulated over thousands of years. In Walla Walla, loess deposits can exceed 30 feet deep in some vineyards, and reach over 100 feet in parts of the broader Columbia Basin near Pullman.
Origins
During and after the Ice Ages, strong winds picked up fine sediments from glacial outwash plains and flood deposits, carrying them across the landscape. This silt settled in thick deposits, particularly on south-facing slopes.
Perfect for Viticulture
Loess soils have remarkable properties for growing wine grapes:
- **Excellent water retention** during dry summers
- **Good drainage** preventing waterlogging
- **Natural fertility** with balanced minerals
- **Easy root penetration** allowing deep vine establishment
The Calcium Carbonate Signature
In the Walla Walla foothills, loess soils carry a hidden feature that sets them apart: calcium carbonate layers deposited 3 to 8 feet below the surface. These formed over thousands of years as summer heat evaporated soil moisture upward through the soil profile, leaving mineral deposits behind in a process called illuviation. The result is a distinct white-chalky layer that influences drainage, root behavior, and mineral uptake — contributing to the characteristic structure of wines grown on foothill sites.
Dry-Farming Country
Near the Blue Mountains, annual rainfall exceeds 20 inches — enough that some foothill vineyards can be dry-farmed, grown without any irrigation at all. In eastern Washington wine country, this is exceptional. Dry-farmed vines develop deeper, more extensive root systems in search of water, and the resulting wines tend toward greater concentration and complexity. It's one of the quieter arguments that Walla Walla's foothills occupy some of the finest vineyard land in the state.
The Walla Walla Advantage
The combination of loess over flood sediments over basalt creates a layered soil profile characteristic of the Columbia Basin. As vine roots penetrate through these layers — and encounter calcium carbonate at depth — they access different nutrients and water sources, contributing to the complexity and mineral character of the wines.