Vernal Pools of the Santa Rosa Plateau Vernal Pools of the Santa Rosa Plateau Vernal is derived from the Latin word for spring. A vernal pool is a spring pool - one that dries up in late spring or summer and therefore doesn't have water in it until winter rains recreate the pool. Vernal pools usually are found in areas where the winter means the rainy season, and summer means the dry season.
Pools fill in winter from the rains, and evaporate in the dry heat of summer.
There are many types of vernal pools in California. The California Wetlands Information System has put together a map showing their distribution. A detailed map of the individual pools in each region along with very detailed descriptions of the type of vernal pools, their protection status, geology, etc. can be reached by clicking on each region. The vernal pools of the Santa Rosa Plateau are the only known examples of Southern Basalt Flow Vernal Pools. The basalt on the Santa Rosa Plateau is the key to the large number of vernal pools there.