Lake County Viticultural Soils

At its core, the nature of Lake County is explained by its wide spectrum of geologic formations. In places, the monumental forces of colliding continents have exposed deep ocean floor rock where serpentine is found. Those same forces have caused folding and uplift of Great Valley Sequence (characteristic of California’s Central Valley), resulting in sandstone and shale. And right under these formations, volcanic processes have broken through the surface and laid down a new landscape.

The viticultural soils of Lake County can be grouped into four broad categories: hillside soils formed on volcanic materials, hillside soils formed on sandstone and shale, terrace alluvial soils, and valley alluvial soils.

Ariel map courtesy of Google.com

Volcanic hillside soils dominate in the Red Hills and the High Valley AVAs. These soils are characteristically gravelly or rocky and very well-drained. Examples include Aiken, which formed on basalt; Arrowhead, which formed on obsidian; and Soda Bay, which formed on scoria, the porous red gravel used in landscaping. Lake County hillside volcanic soils are red, a color often associated with old, highly weathered soils. However, the Clear Lake volcanics are recent in geologic origin. The scoria formations near High Valley and the lower arm of Clear Lake are as young as 10,000 years.

Glenview-Arrowhead complex was formed on obsidian.

Hillside soils formed on sandstone and shale are found on mountains thrust up from an ancient sea floor. These soils are well-drained and frequently shallow, with underlying sandstone found at a depth of two to four feet. These soils are yellowish-brown in color and well-suited to red grape varieties. Common soil types include Maymen, Mayacama, and Hopland.

Alluvial terraces were formed by a combination of geologic uplift and river down-cutting, resulting in a relatively level and well-drained landscape. These terraces are found throughout Lake County, circling valleys and Clear Lake. Many of these soils have weathered to a deep reddish color, leaving a lean soil well-suited to wine growing. Some of the Lake County soils formed on alluvial terraces include Jafa, Forbesville, and Manzanita.

Mountain valleys around Clear Lake, including Big Valley District, Upper Lake Valley, Clover Valley, Bachelor Valley, and Scotts Valley, are level with deep alluvial deposits. The soils often have layers with differing gravel content and amounts of sand, silt, and clay, created by the movement of stream courses in the past. Well-drained alluvial soils found in these areas include Still, and Lupoyoma loams, which produce some of Lake County’s famous Sauvignon Blancs.

Calendar of Events

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LCWC Board Meeting 4:00 pm
LCWC Board Meeting @ LCWC Office
Dec 3 @ 4:00 pm – 5:15 pm
Agenda – LCWC Board Meeting, December 3, 2019
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Crop Insurance Webinar Series 10:00 am
Crop Insurance Webinar Series
Dec 4 @ 10:00 am – 11:00 am
Crop Insurance Webinar Series
Crop Insurance 101 As the harvest season wraps up, it’s time to start planning for next year. An important part of your 2020 planning process is risk management of your most valuable asset – –[...]
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Crop Insurance Webinar Series 10:00 am
Crop Insurance Webinar Series
Dec 11 @ 10:00 am – 11:00 am
Crop Insurance Webinar Series
Crop Insurance 102 Whether you are new to crop insurance or you’ve been purchasing it for many years, CAWG is committed to bringing you education on the most current industry topics. Our Crop 102 webinar[...]
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UCCE Lake & Mendocino IPM Seminar 7:30 am
UCCE Lake & Mendocino IPM Seminar @ UC Hopland Research and Extension Center
Dec 13 @ 7:30 am – 5:00 pm
22nd Annual UCCE Lake & Mendocino IPM Seminar   UC Hopland Research and Extension Center 4070 University Road, Hopland Rod Shippey Hall Friday, December 13, 2019 Doors open 7:30 am for Registration Seminar starts at[...]
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Crop Insurance Webinar Series 10:00 am
Crop Insurance Webinar Series
Dec 18 @ 10:00 am – 11:00 am
Crop Insurance Webinar Series
Whole Farm Revenue Protection Want to protect your crop against price and market losses? Maybe Whole Farm Revenue Protection (WFRP) is for you! Join CAWG on Wednesday, December 18th at 10:00 am to learn more[...]
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