page_title: Calabazas Creek (Sonoma County)
section_title: Geology
hierarchical_section_title: Calabazas Creek (Sonoma County) / Geology
caption_attribution_description: English: Arbutus menziesii — Pacific Madrone Showing shallow rooting in a road cut area in the upper watershed of Calabazas Creek in the Mayacamas Mountains, Sonoma County, California. Credits high res version date 2007 photographer releases all rights
context_page_description: Calabazas Creek is a 5.5-mile-long stream in the Sonoma Valley, California, United States, that rises in the southern Mayacamas Mountains and empties into Sonoma Creek near Glen Ellen.
context_section_description: Up until about twelve million years ago, this location was part of the seabed of the Pacific Ocean. In the Miocene era, precipitated by the combination of tectonic movement due to the seismically active environment and the presence of magma not far below the Earth's surface, a massive period of uplift ensued. This uplift formed the volcanically based Mayacamas Mountains. Residual evidence of these ancient geological features appears in the form of scattered outcrops of basalt and rhyolite as well as local hot springs such as nearby Mortons Hot Springs and Agua Caliente Hot Springs. Some rock quarrying was historically conducted near Nunns Canyon Road in the upper Calabazas Creek watershed.
caption: Madrone tree in upper watershed of Calabazas Creek, showing shallow rooting due to thin soil mantle.
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