Mount St. Helens is a complex volcano with a long history of eruptions, which has resulted in multiple layers of different materials. It's challenging to label all the layers precisely without detailed geological surveys and analysis. However, we can broadly categorize the layers based on general knowledge of volcanic activity:

1. Pre-1980 Eruption Layers:

* Older Volcanic Rocks: These are the oldest layers, composed of various volcanic rocks like lava flows, ash deposits, and pyroclastic flows from previous eruptions over thousands of years.

* Sedimentary Rocks: In some areas, older sedimentary rocks might be found, deposited before volcanic activity began.

2. 1980 Eruption Layers:

* Pyroclastic Flows: This layer is predominantly composed of hot, fast-moving mixtures of gas, ash, and rock fragments deposited by the devastating 1980 eruption. This layer is readily recognizable due to its characteristic "welded" texture.

* Lahars: These are mudflows, a mixture of volcanic debris and water, deposited by the eruption.

* Ashfall: Fine volcanic ash that settled across the landscape, often forming distinct layers.

3. Post-1980 Eruption Layers:

* Lava Flows: Since the 1980 eruption, new lava flows have emerged from the crater, creating dome-shaped features.

* Ash Deposits: Smaller eruptions since 1980 have deposited ash layers, creating distinct strata.

Note:

* The exact composition and thickness of these layers can vary greatly across the volcano, making it challenging to generalize.

* Specific layers might require detailed geological mapping and analysis to be fully identified.

To obtain a more accurate and detailed classification, you would need to consult geological studies and maps specifically focused on Mount St. Helens. The U.S. Geological Survey (USGS) is a valuable source for such information.