Boosted by a booming aerospace business that is expected to continue growth in the 1980s, Martin Marietta Corp. yesterday reported record sales and profits for the fourth quarter and all of 1980.

Although profits did not match 1979 record levels in other divisions of the diversified Bethesda corporation, aerospace sales more than made up for the recessionary impact as overall fourth-quarter net income rose to $43.5 million ($1.74 a share) compared with $37.3 million ($1.50) a year earlier. Revenues were $711.0 million compared with $569.4 million.

Net income for the year was $188.1 million ($7.55) compared with $178.0 million ($7.10). Revenues rose to $2.6 billion from $2 billion.

Chairman J. Donald Rauth said the aerospace performance was "excellent . . . its best ever as anticipated . . . we are confident that trend will continue."

Cement division sales were off slightly and profits were down sharply, while sales in the chemicals, aluminum and construction aggregates divsions all expanded and profits in these three areas were not equal to the prior year, Rauth added.

Ethyl Corp. of Richmond reported a 12 percent gain in fourth-quarter profits although earnings for all of 1980 were down 8 percent.

Fourth-quarter net income was $24.68 million ($1.21 a share) a year earlier on sales of $431.59 million compared with $22 million ($1.07) a year earlier on sales of $431.05 million.

Net income for the year was $89.68 million ($4.39) on sales of $1.74 billion compared with $97.51 million ($4.77) in 1979 on sales of $1.657 billion.

Chairman F. D. Gottwald Jr. said a very weak third quarter caused the earnings shrinkage for the year.

First American Bank of Virginia reported record fourth-quarter earnings of $2.4 million ($1.40 a share), up from $2.0 million ($1.21). Earnings for the year were a record $.91 million ($5.39) compared with $8.2 million ($4.89), at the largest bank in Northern Virginia, a unit of the Financial General Bankshares Inc. holding company.

The bank's average loans for the year were $474.5 million, up from $432.1 million. Deposits wer $77.5 million compared with $714.7 million.

First and Merchants Corp. of Richmond, a statewide holding company, reported record fourth-quarter and year-end earnings caused mostly by higher net interest income, the company said.

Income before securities transactions for the quarter was $4.4 million ($1.34 a share), ujp from $3.9 million ($1.17). Operating profits for the year were $16.5 million ($5.05), up from$15.2 million ($4.58).

Net income for the quarter was $3.1 milion (94 cents), down from $3.4 million ($1.02). For the year net income was $14.8 million ($4.53) compared with $13.6 million ($4.09).

Total average assets for the year were $2.2 billion, up from $2.1 billion a year ago; loans were $1.3 billion up from $1.2 billion; and average deposits were $1.7 billion, up from $1.6 billion.

First Maryland Bankcorp reported fourth-quarter oprating net income before securities transactions of $5.2 million ($1.12 a share), up from $4.7 million ($1.01). Income before securities tranactions for the year was $2.8 million ($4.46) compared with $18.9 million ($4.04) at the Baltimore holding company for First National Bank of Maryland.

Ryland Group Inc. of Columbia reported decreased fourth-quarter earnings of $2.2 million (69 cents a share) compared with $2.6 million (83 cents). Revenues of the home builder were $85.2 million, up from $74.9 million. Earnings for the year also decreased from $7.9 million ($2.48) to $6.6 million ($2.12). Revenues for the year were $258.0 million, up from $244.6 million.

Schwartz Brothers Inc., which owns Harmony Hut record stores, reported a loss of $63,463 in its third quarter ended Oct. 31 compared with a loss of $188,505 the year before.Revenues were $8.34 million compared with $7.68 million a year earlier.

Wapora Inc., an environmental and energy-control research firm based in Chevy Chase, announced that net income increased to $135,082 (23 cents a sahre) from $94,508 (14 cents) for the six months ended Dec. 31. Revenues rose to $3.84 million from $3.36 million a year ago.

Student Loan Marketing Association (Sallie Mae) annonced a 49 percent increase in net earnings for 1980 to $9.4 million ($56.64 a share) from $6.3 million ($38.08) in 1979. Fourth-quarter net income was up 31 percent to $2.9 million ($17.21) from $2.2 million ($13.16) during the previous year.