Actually, Bruce, in my area of California, the opposite is true. This being an oil-producing region, most of the oil and mineral rights (and usually riparian rights as well) were leased to the oil companies back in the 20's and 30's but with no right to drill on said property while the clear title to the land remained with the homeowner. Often when the owner sold the property, he retained the oil/mineral/riparian rights in order to continue receiving monthly royalty fees from oil companies, and these rights were then excluded from the titles to the land. Probably 90% of the transactions I did, the titles no longer contained oil/mineral/riparian rights -- the only ones that did were properties that hadn't sold in a very long time. Only once did I sell a property where the oil rights were still with the title and the seller retained those rights, thus separating them from the title to the land.
The situation you describe in California may exist in other areas of the state, but certainly is not dictated by California real estate law since it doesn't exist in my area. I have never seen a Warranty Deed.
Newly