• Sunset at Lake Mead's Boulder Basin

    Lake Mead

    National Recreation Area AZ,NV

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    The Nevada Department of Transportation reopened a northbound and southbound lane of Interstate 15 Sept. 12; therefore, Lake Mead National Recreation Area entrance fees will resume Sept. 14. More »

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  • Areas of Park Impacted by Storm Damage

    Strong storms rolled through Lake Mead National Recreation Area Aug. 3-4, causing damage to some areas of the park. Crews are working to restore the below locations. Debris may be present in other areas of the park, as well, especially in the backcountry. More »

Hamblin-Cleopatra Volcano


Along the north shore of Lake Mead exists an ancient volcano, long dormant but very intriguing. The Hamblin-Cleopatra Volcano (HCV) was once a large stratovolcano and now has split into three large sections due to earthquake faults in the area.

The volcano formed in the late Miocene time and through the years slowly split in half, and then parts of the Cleopatra section split again, separating the original volcano complex by twelve miles. The original volcano was more than 3,000 feet high and had a circular width of approximately eight miles. It’s formation was rapid.

Area Map


What is a Stratovolcano

Illustration by Anthony Ross

Originally the Hamlin-Cleopatra Volcano was a stratovolcano, which is the most common type. Other stratavolcanos are Mount Vesuvius in Italy, Mount St. Helens in Washington State, Mount Shasta in Northern California, and Mount Fuji in Japan.


History of Hamblin-Cleopatra


Around 13 million years ago, Hamblin-Cleopatra were one large stratovolcano. The volcano sat on the Hamblin Bay Fault which ran right through the middle of the mountain, splitting it in two. For clarity the Hamblin Mountain portion is in light red, the Cleopatra portion in light green, and the Cleopatra split-off is colored grey.


Over the millions of years since the volcano has been active the movement of the Hamblin Bay Fault moved the Hamblin portion to the southwest and the Cleopatra terrain to the northeast. Another fault formed that split the Cleopatra lobe in two.


Currently the Cleopatra lobe is around 12 miles from the Hamblin Mountain lobe. You can see in the color coded USGS map below the distinct locations of the three parts of the Hamblin-Cleopatra Volcano as it is today (Dark Magenta color)

Thematic Geology Map of Hamblin-Cleopatra area.
Courtesy of USGS

Photo Gallery



Geologic Map by United States Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_81106.htm

DOI Paper, Large-Magnitude Late Tertiary Strike-Slip Faulting North Lake Mead, R Ernest Anderson. 1973


Did You Know?

Jimbilnan Wilderness - taken by Brian Beffort

"In a country where nature has been so lavish and where we have been so spendthrift of indigenous beauty, to set aside a few rivers in their natural state should be considered an obligation." -- Senator Frank Church