From Mosley's pamphlet, "The Hugo Ballin Murals at the Griffith Observatory" (Los Angeles: Published by the Griffith Observatory, Department of Parks and Recreation, City of Los Angeles, 1998):

“The panel above the entrance of the East Gallery features the earth and its life.

The ancient man at left symbolizes geology. He holds a card that shows various crystalline forms of minerals. Below him are snow-capped mountain peaks wreathed in clouds. Behind him are sharply folded layers of rock showing stratification. A drilling rig which extracts oil trapped within rock layers is at extreme left. Oil production was important in Southern California in Ballin’s time, as well as today. Huge crystals are in the background, below rolling ocean waves.

At the center a biologist, flanked by a skull on a book and a box of slides, peers into a microscope. Below him are the embryo of a chicken on the sixth day, and a crab. The crab is holding a cactus in bloom. Beside the crab are spores as seen through a microscope. 

The robed figure at right symbolizes paleontology, the branch of geology that deals with life in the past geological ages. He holds a painting of the skull of a saber-toothed cat, a prehistoric animal found in the La Brea Tar Pits in west Los Angeles. The skeleton at his feet belongs to an early type of fish. The waves of water barely visible at the bottom symbolize the origin of life, which began in the sea, while the man and a woman above are looking upward for the answer to the meaning of life.”

In this panel, Ballin employed allegorical figures to represent three scientific disciplines: paleontology, biology and geology. Each bows his head, placing the emphasis on the symbols of his field depicted below. The composition in more disjointed than others included in the observatory murals, held together only by the repetition of the three central figures, and Ballin employs a fairly odd set of symbols and motifs, making this panel more abstract in its style. The central figure, representing biology, is more realistic than the others, and appears younger in age and more modern in his costume and equipment, suggesting Ballin believed that discipline to be more "modern" than the other two.

Caption excerpted from John Mosley's pamphlet, "The Hugo Ballin Murals at the Griffith Observatory" (Los Angeles: Published by the Griffith Observatory, Department of Parks and Recreation, City of Los Angeles, 1998).