Thousands of chanting; sign-waving demonstrators accompanied by more than 100 huge logging trucks clogged this small coastal community today to protest plans to expand federal holdings of giant redwood trees in northern California.

Nearly 8,000 marchers in hard hats and work clothes snaked through Eureka's downtown business section signing "God Bless America" and chanting "We want jobs" and "No more parks."

No violence was reported by police during the two-hour demonstration, but emotions over the planned expansion of Redwood National Park have been running so high that Eureka's entire 60-member police force plus county and state police were assigned to monitor the march route and shut off most of the city's business district.

Virtually all other activity in this city of 24,000 came to a halt during the demonstration, which was called to coincide with the opening of field hearings here by tyh House Subcommittee on National Parks and Insular Affairs on the expansion plan.

Demonstration leaders said they planned to drive the big trucks - some of them loaded with heavy logging machinery and five-foot-wide sections of already out redwood, tree trunks - to San Francisco, down 200 miles to the south of here. The trunks are scheduled to arrive during San Francisco's crowded morning rush hour for the second day hearings by the sub-committee there on Thursday.

"This hearing and this gathering has to send the message throughout the country that we are going to fight to keep our jobs," said Rep. Donald Clausen (R-Calif.), a subcommittee member who represents this timber-rich area stretching north to the Oregon border.

Clausen told the crowd gathered in front of the Humholdt County court-house here this morning that the plans for adding 77,500 acres of redwoods to Redwood National Park about 40 miles northeast of here was "no more than a smokescreen" for a land grab."

A general park expansion plan has received the blessing of the Carter administration. Last month Interior Secretary Cecil D. Andrus called on the three logging companies working the expansion area to halt operations for 180 days while details of the new park area are worked out.

However the Simpson Timber Co., the Lousiana-Pacific Corp. and the Arcada Redwood Corp., which own most of the land in the park expansion area, rejected the moratorium suggestion.

The companies are logging within a half mile of the park border and a grove of redowods that includes the tallest trees in the world. Spokesmen for the lumber firms claim economic pressures and a lack of alternative logging sites require redwood cutting in the expansion area.

Rep. Phillip Burton (D-Calif.), chairman of the subcommittee and sponsor of the branches of the three expansion proposals, drew a chorus of catcalls and boss from logging proponents today when he said he was "sickened" after viewing the redwood cuts in the expansion area from a helicopter yesterday. The congressman said he would speed passage of the expansion legislation becuase the companies were not honoring the moratorium.

Burton, whose district is in San Francisco, has proposed a 77,500-acre park. Two other expansion plans would add 21,000 acres and 47,000 acres respectively. Andrus has not indicated which of the plans he favors.

Rep. Clausen told more than 2,300 persons who jammed into the hearing here that between 1,030 and 2,230 jobs out of the area's 8,000 logging industry jobs would be lost, depending on the size of the expansion.

Northern California's coastal timber area has nearly 15 per cent unemployment, and logging proponents claim it would jump to more than 25 per cent if the park expansion goes through. Nearly 80 per cent of the area's economy is tied to the timber industry.

Supporters of the park expansion warn that without it the park's "tall trees grove," containing trees over 350 feet high and 2,000 years old, would be harmed by erosion.