Greenhouse Portal

Greenhouse Portal (HM1RH2)

Location: Pittsburg, CA 94565 Contra Costa County
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Country: United States of America
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N 37° 57.297', W 121° 51.928'

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A Hidden World Awaits

Take a moment and gaze down the Greenhouse Portal, your entrance into vast underground spaces filled with an intriguing human and geologic history. What was once the ocean floor provided raw materials (silica sand) for glass making during the early twentieth century.
When R. Marvin Greenhouse began hollowing these hills to mine the silica sandstone, he could not have known that the cavernous rooms left behind would fascinate people for decades to come.
Today this portal serves as your gateway to the past and entrance into a unique underground visitor center. Join us during open house, and step into the earth and into the past.
HM NumberHM1RH2
Placed ByEast Bay Regional Park District
Marker ConditionNo reports yet
Date Added Tuesday, April 5th, 2016 at 9:01am PDT -07:00
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Locationbig map
UTM (WGS84 Datum)10S E 599671 N 4201423
Decimal Degrees37.95495000, -121.86546667
Degrees and Decimal MinutesN 37° 57.297', W 121° 51.928'
Degrees, Minutes and Seconds37° 57' 17.82" N, 121° 51' 55.68" W
Driving DirectionsGoogle Maps
Area Code(s)925, 510, 415
Closest Postal AddressAt or near Nortonville Rd, Pittsburg CA 94565, US
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