Here's a breakdown:
* Lava Flow: The cooled and solidified lava itself. The shape and characteristics of the lava flow depend on the type of lava (basaltic, andesitic, rhyolitic, etc.) and the terrain it flows over.
* Lava Flow Margin: This is the edge of the lava flow where it meets the existing rock. It often has a sharp, defined boundary and can take on various forms:
* Columnar Jointing: If the lava cools slowly, it may develop vertical cracks forming columns, like hexagonal prisms.
* Pahoehoe: Smooth, ropy, or billowy surface texture.
* A'a: Rough, jagged, and blocky surface texture.
* Pillow Lava: Rounded, pillow-like shapes formed when lava flows underwater.
The lava flow margin provides valuable information about the direction and path of the lava flow, the speed of the eruption, and the type of volcanic activity that occurred.
