TORONTO (CP) - The rock and folk music recording industry, once the preserve of artists from the United States and Great Britain, now is having its surface scratched by talented Canadians.

The inroads have been three-pronged.

Singers, composers and musicians such as David Clayton-Thomas, Joni Mitchell and Steppenwolf have begun their careers in this country and have moved on to greater success in the U.S.

Others like Robert Charlebois of Montrea1, Gordon Lightfoot and The Motherlode, both of Toronto, and The Guess Who of Winnipeg have achieved popularity in the U.S. while remaining in Canada.

Then there is the paradox of Ronnie Hawkins of Fayetteville, Ala., who left the U.S. to come to Toronto in 1958. With his Yonge Street nightclub, Rompin' Ronnie has become one of the biggest boosters of Canadian pop talent.

Among those cutting the biggest grooves in the industry are The Guess Who. The quartet this year became the first Canadian group in nearly 10 years to sell 1,000,000 records. Their RCA disc, With These Eyes, has to date sold 1,250,000 and the group has recorded two albums, Canned Wheat and Wheatfield Blues.

Success was not immediate for the group, made up of vocalist Burton Cummings, guitarist Randy Bachman, bassist Jim Kale and drummer Gary Peterson.

"For years we issued records and they were released in the U.S. as well as Canada," Bachman said in an interview. "We used to cry to each other because the American radio stations would not play the records.

"Now we have the biggest radio stations phoning us at home. ... It's really flabbergasting."

A more recent success is that of The Motherlode, whose single recording When I Die has moved to Top 40 lists in the U.S. The group was formed earlier this year by saxophonist Steve Kennedy from Windsor, Ont. and now includes singer William Smith from Belleville, Va., drummer Wayne Stone of London, Ont., and guitarist Kenny Marco of Brantford, Ont.

Also popular are recordings by two new Canadian groups. Hear The Grass Grow by The Eighth Day, and Groovy Things by The Magic Cycle, and I Got Stung by composer-singer Bonnie Dobson of Toronto.

Composer-singer Andy Kim of Montreal came to attention in the U.S. last year with his first record, How'd We Ever Get This Way. He followed this with Shoot 'Em Up Baby, which one Steed Record Co. official said had marginal success because of a summer of civil rights disturbances. But his composition Rainbow Ride was recorded as a single and then as part of an album.

One of the most unusual Canadian pop singers is Robert Charlebois, the flamboyant 24-year-old Montrealer who has been known to hurl epithets and sometimes musical instruments at his audience.

His recent single, Lindbergh, sung in a half-French, half-English dialect, sold about 250,000 copies in the U.S. and Canada.

Charlebois has cursed "les Anglais" before English speaking audiences, jeered about separatism to French-Canadian crowds, and chided audiences in France for their provincialism.

"I'm beginning to be a star and that scares me. ... I fill the hall. I am beginning to be a consumer product. Even if I know that this is to a certain extent inevitable, I don't want to take pleasure in it. I don't want to end my shows with the Lindbergh hit. That would be too easy ... but I have something else to say."

Ronnie Hawkins, who achieved his first popularity among Canadians because he was an American and later with his recorded version of Early Morning Rain by Gordon Lightfoot, recently signed a $500,000, five-year recording contract with Atlanta Records. He plans to use some of the money to boost Canadian pop talent.

"We want to start an all-Canadian record company," he said.

Steppenwolf, the rock quintet that took their name from the Herman Hesse novel of the 1920s, started in Toronto in the 1960s under the name Sparrow. Lead singer John Kay, a Californian, joined the group while they were playing at Yorkville district coffeehouses. Sparrow moved to California in 1966, took the new name, and has since sold more than 2,750,000 copies of two recordings, Magic Carpet Ride and Born To Be Wild.

David Clayton-Thomas, like Steppenwolf, got his start in Toronto. Born in London, England, Clayton-Thomas grew up in Toronto and formed a group called The Bossmen with which he recorded and toured the country for five years. Last year he joined Blood Sweat and Tears in New York.

But at least one of the expatriates has shown an interest in returning.

Joni Mitchell, the prolific song writer from Fort Macleod, Alta., who left Canada two years ago for New York and later Los Angeles, said in a recent interview here:

"Returning is sometimes a great relief. The pace of life is not so frantic as it is in the States. I find that the demands of concert tours are leaving me less and less time to write music - which is really what I want to do."

Since moving to Los Angeles, she has recorded two albums for Reprise Records and is reported to receive up to $5,000 for concert appearances. Her composition Both Sides Now has become standard among the repertoire of popular and folk singers and has been recorded by Frank Sinatra, Judy Collins and Harry Belafonte.