1. Composition:
* Lava mesas and buttes: Often composed of volcanic rock like basalt, rhyolite, or andesite. These rocks are typically dark in color and may have a distinctive glassy texture.
* Sedimentary mesas and buttes: Formed from erosion of sedimentary rock layers like sandstone, limestone, or shale. These rocks tend to be lighter in color and have a more granular texture.
2. Shape and Structure:
* Lava mesas and buttes: Often have a more rounded or dome-like shape. They may also exhibit features like lava flows, volcanic vents, or cinder cones.
* Sedimentary mesas and buttes: Typically have more angular and layered structures, with cliffs and canyons formed by erosion.
3. Surrounding landscape:
* Lava mesas and buttes: May be surrounded by other volcanic features such as lava fields, calderas, or volcanic mountains.
* Sedimentary mesas and buttes: Tend to be found in areas with other sedimentary landforms like canyons, plateaus, and mesas.
4. Evidence of volcanic activity:
* Lava mesas and buttes: May show signs of volcanic activity like:
* Columnar jointing: A distinctive pattern of vertical cracks in the rock, often found in cooled lava flows.
* Lava tubes: Hollow tunnels formed by flowing lava.
* Volcanic bombs: Large, ejected fragments of volcanic rock.
5. Geological mapping and analysis:
* Geological maps: May provide information about the rock types and geological history of the area.
* Rock analysis: Petrographic analysis of rock samples can reveal their origin and composition.
It's important to note: In some cases, the origin of a mesa or butte may be ambiguous. For example, a volcanic feature might be later eroded and modified by other geological processes, making its origin difficult to determine.
In summary: To determine if a mesa or butte was formed by lava, look for evidence of volcanic rock composition, rounded shapes, volcanic features, and other signs of volcanic activity.
