Columbia-based Ryland Group has announced a pre-tax fourth quarter earnings charge of $13 million that is expected to have a negative impact on the company's end-of-year profits.

The earnings charge is a result of land- and market-related problems with two Ryland joint-venture residential developments in California, officials said.

Ryland said it reserved $10 million as a result of its investment in a joint-venture community in Riverside County, Calif., due to soil-stability conditions in the region, which may require substantial engineering and regrading of the site. Also, officials said, a continuing weak market has forced the company to discontinue the second phase of another joint-venture project in Southern California, resulting in an additional $3 million earnings charge.

Roger W. Schipke, chairman and chief executive officer, said that despite the charges the company expects to be marginally profitable during the fourth quarter. Those earnings results should be released by February.

In its third quarter, Ryland's net earnings rose 20 percent to $6.9 million, or 49 cents a share. The company's financial-services operations had a pretax earnings gain of 52 percent over the third quarter of 1990 and continue to move toward a record year.