Uploaded January 2022 | Updated September 2026, 2 weeks ago
Petroglyph Point is an imposing cliff marked with the cultural symbols of the Modoc People, who have lived here for thousands of years. What is this giant rock and what made it so good for carving petroglyphs? Find out on BetterGeology!
••• Videos are posted a day early over on my Ko-fi: ko-fi.com/bettergeology •••
Petroglyph Point is a tuff-ring, which is a type of volcano formed when magma meets water. The Tule Lake area was once part of the huge Lake Modoc during the last Ice Age, which extended far to the north and east from here. 275,000 years ago, magma related to the vast Medicine Lake Volcano erupted at a point under the lake, which caused a steam-driven explosion of lava, water, and rock to make a series of islands (one of which hosted a short-lived lava lake) in Lake Modoc. Over time, wind and wave action carved the soft rock into imposing cliffs in the middle of the now-shallow Tule Lake. Ancient Modoc people canoed out to these islands and left their cultural symbols all over these cliffs, which varied in height with the lake through time.
The Modoc were forced from their homes in brutal guerrilla wars in the 1870s; though some remain living in the Modoc Plateau to this day, the scars of that crime remain across the landscape.
Petroglyph Point is an imposing cliff marked with the cultural symbols of the Modoc People, who have lived here for thousands of years. What is this giant rock and what made it so good for carving petroglyphs? Find out on BetterGeology!
••• Videos are posted a day early over on my Ko-fi: ko-fi.com/bettergeology •••
Petroglyph Point is a tuff-ring, which is a type of volcano formed when magma meets water. The Tule Lake area was once part of the huge Lake Modoc during the last Ice Age, which extended far to the north and east from here. 275,000 years ago, magma related to the vast Medicine Lake Volcano erupted at a point under the lake, which caused a steam-driven explosion of lava, water, and rock to make a series of islands (one of which hosted a short-lived lava lake) in Lake Modoc. Over time, wind and wave action carved the soft rock into imposing cliffs in the middle of the now-shallow Tule Lake. Ancient Modoc people canoed out to these islands and left their cultural symbols all over these cliffs, which varied in height with the lake through time.
The Modoc were forced from their homes in brutal guerrilla wars in the 1870s; though some remain living in the Modoc Plateau to this day, the scars of that crime remain across the landscape.
