Jules Marcou was a world-famous geologist. He was born in France on April 20, 1824 and died in Cambridge, Massachusetts on April 17, 1898. He came to America in 1847 and, in the following year, worked with Louis Agassiz in the Lake Superior region. In 1837, Agassiz had been the first person to propose that the earth had been subject to a past ice age.
Marcou spent two years studying the geology of parts of the United States and Canada. In 1853 he was one of the geologists of the Pacific Railroad Survey of the thirty-fifth parallel. In 1853, he published a Geological Map of the United States and the British Provinces of North America.
In 1853 he returned to Europe and in 1855 he became professor of geology and paleontology at the Polytechnic School of Zurich. In 1861 he published a Geological Map of the World. In 1861 he returned to America and assisted Agassiz in the founding of the Museum of Comparative Zoology in Cambridge, Massachusetts, where he was in charge of the division of paleontology.
Now, what did he do for us? Marcou was a geologist for the California section of the Army Corps of Engineers survey of the 100th Meridian in 1875. In the "Annual Report on the Geographical Surveys west of the 100th Meridian" by 1st Lieut.George M. Wheeler, Corps of Engineers, published in 1876, Marcou wrote a paper called "Report on the Geology of a Portion of Southern California" (1.1MB).
Most of it will not be of interest to you. However, on report pages 161 and 164 he mentions Lyon's Station or Petroleopolis and reports on the geology of the San Fernando Pass area. Also, on page 164 and 165, he talks about "Mr. Lyon's petroleum-spring" also known as Pico's Spring. Then he mentions the Towsley Canyon claim calling it "Temple's Oil-Wells." Finally, he mentions Moore's Station near the San Francisquito ranch. To me, this first-hand information is historically and geologically interesting.
Jules Marcou's gravesite in the Mount Auburn Cemetery in Cambridge, Massachusetts