Left Panel: This was once the site of Throop Hall, named after the founder of Throop University, Amos G. Throop. Throop University was founded in 1891 and became the California Institute of Technology in 1920. Built in 1910, Throop Hall was the first building on this campus.
The rocks displayed throughout Throop Memorial Garden represent nearly two billion years in the geological history of California. They were brought here from the San Gabriel Mountains, the backdrop to CalTech and Pasadena where Amos G. Throop and his family played an important role.
This exhibit is made possible through the generosity of Martha Vaughan Smith, great-granddaughter of Amos G. Throop.
Right Panel: The boulders in Throop Memorial Garden are grouped according to type and age, given in millions of years. Representative locations for such rocks are also indicated.
I. Rocks numbered 2, 9, 15, 17, 21, 22, 26-29, 34, 35, 39, 49, 52, 55, 57; ancient gray gneisses found on Brown Mountain and at 3,000-4,000 ft. elevations near Angeles Crest Highway; more than 1,700 million years old (MY).
II: Rocks 3, 4, 14, 16, 20, 25, 38, 42, 58, 63-65, 70; oldest generation granite, closely associated with Brown Mountain gneisses; approx. 1,650 MY.
III: Rocks 19, 32, 33, 44, 45, 56, 59, 60, 66; sheared granites, lighter varieties, found on Mt. Lowe, above 4,000 ft; rocks 11, 43, 46; darker varieties, Bear Canyon tributaries; approx. 220 MY.
IV: Rock 37; distinctive pink granite, underlies Echo Mountain, visible on Millard
Canyon trail; approx. 160 MY.
V: Rocks 6, 12, 21, 24, 31, 53, 61, 62, 67, 69, 71, 72; relatively unsheared granite from Arroyo Seco canyon; 75 to 80 MY.
VI: Rocks 5, 7, 8, 50, 51, 68, 73; distinctive uniform gray granite, underlies Mt. Wilson; 75 MY.
VII: Rocks 36, 47, 48 (light), and rocks 13, 30, 54 (dark); these mysterious rocks were obtained from the Arroyo Seco, but were clearly transported there by Man. Their original sources and ages are unknown.
VIII: Rocks 40, 41; pseudoliths; 12+ years.
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