That's Carole Lombard with William Boyd in a publicity still from "High Voltage," one we know was shot in the Sierra Nevada mountains because here's a photo of the cast on location:
For Carol (then without an "e" in her first name) and crew, this was considered something special. It was Lombard's first all-talking picture, shot in 1929...when it was rare for a "talker," as sound pictures were then occasionally dubbed, to go on location. Capturing sound was deemed difficult.
It's often been noted that while sound brought an entirely new dimension to Hollywood films, it also forced the industry to retrench to square one where technology was concerned. No one really yet knew how to master the altered medium, so consequently films -- which had become increasingly artistic in later silent days -- became stagy and claustrophobic. (Even inside the confines of the studio, things were relatively static; most early talkies lack camera movement, and some of the revues or stage show adaptations look as if they were shot from an orchestra-level seat 20 rows away -- not at all interesting cinematically. It may have been a major reason why musicals fell out of favor around 1930, not regaining popularity for another few years.)
As one reporter of the time noted,
"...it was impossible to cut out extraneous unwanted sounds that ruined many scenes. If outside atmosphere was wanted it required a very expensive expedition with cumbersome apparatus. After time and money had been spent to film a scene in a distant location, results were often so unsatisfactory that the entire footage would be discarded. Portable sound apparatus could only be carried in heavy trucks on paved roads, and was continually getting out of order, due to the jolting of the truck."
One would guess that the Sierra Nevadas were so isolated then that there was next to no "extraneous unwanted sounds" -- something that couldn't be said for most outdoor locations. You can be certain that Pathe officials didn't take this expense lightly.
However, imagination and technology walked hand in hand in Hollywood, and by 1932, it had become far easier for filmmakers to shoot exteriors for movies (no need to say "talkies" anymore; unless you were named Charles Chaplin, the silent film was extinct). Credit something called the "directional microphone."
Moreover, sound equipment gradually became lighter and less bulkier to transport, making it significantly easier to take it on location. And the huge variety of locations in southern California -- one of the things that had lured filmmakers to the place two decades earlier -- came back into play. There were a number of favored sites, according to MGM location manager Louis Strohm:
“Among the most popular nearby location spots is the Malibu mountain country, the Chatsworth hills and Bel-Air hills, Laguna Beach and the Arrowhead mountain country. All these places are so near Hollywood that a director can take his troupe out for an afternoon’s location excursion, and all are off the main airplane routes and traveled highways.”
Another popular site was the Los Angeles city reservoir, Lake Franklin. It was frequently used in movies, such as "Susan Lenox: Her Fall And Rise," the only film pairing of Greta Garbo and Clark Gable:
Several of Gable's early films took full advantage of the technology boost, including "A Free Soul" (part of which had scenes at Yosemite National Park) and "Hell Divers" (which spent several weeks filming near San Diego and also used the coves at Laguna Beach).
To see the entire story, which ran in late April 1932 -- and learn about some popular outdoor silent-era sites that didn't make successful venues for sound -- visit the fine retro site "Hollywood Heyday," specifically http://hollywoodheyday.blogspot.com/2010/07/locations-for-pictures.html