Sequence of geological events in three cross-sections, illustrating rock layer formation and relative ages.

Based on the zoomed-in view of cross-section 6, I can analyze the sequence of events.

Analysis of Cross-Section 6:

This cross-section shows several rock layers labeled A, B, C, D, and E, with some faults or intrusions.

1. Layer at the very bottom: This is the oldest layer.
2. Layer above it: Deposited next.
3. Layer above that: Deposited next.
4. Layer above that: Deposited next.
5. Layer A: This appears to be the topmost layer, deposited after erosion occurred (note the irregular boundary).

There are features labeled B, C, and E that cut through the layers:
- Feature B cuts through several layers, indicating it's younger than those layers.
- Feature C also cuts through several layers, indicating it's younger than those layers.
- Feature E cuts through several layers, indicating it's younger than those layers.

Looking at the relationships:
- The bottom-most layer is the oldest.
- Each successive layer above is younger.
- Features B, C, and E are all intrusions or faults that cut through multiple layers, so they must be younger than the layers they cut.

The sequence from oldest to youngest is:
Bottom layer → Next layer up → Next layer up → Next layer up → Feature E → Feature B → Feature C → Layer A

Wait, let me reconsider this. Looking more carefully at the diagram, I need to identify which layers are continuous and which are cut by the features.

Actually, looking at the diagram again, I see that:
- There are several distinct layers from bottom to top.
- Features B, C, and E appear to be faults or intrusions that cut through these layers.
- Layer A is at the top.

The correct sequence should be:
1. The bottom-most layer (unlabeled, but oldest)
2. The next layer up
3. The next layer up
4. The next layer up
5. Feature E (cuts through the lower layers)
6. Feature B (cuts through the lower layers and possibly E)
7. Feature C (cuts through the lower layers and possibly B and E)
8. Layer A (topmost layer)

However, I need to be more precise. Let me re-examine the diagram to determine the exact sequence.

Actually, looking at the diagram again, I see that features B, C, and E are all cutting through the same set of layers, and layer A is deposited on top after erosion. The key is to determine the relative timing of B, C, and E.

Since all three features cut through the same layers, they likely occurred around the same time or we need to look for additional clues. However, without more specific information, I'll assume they occurred in the order they are labeled (E, then B, then C) based on their positions.

The final sequence from oldest to youngest is:
Bottom layer → Next layer up → Next layer up → Next layer up → Feature E → Feature B → Feature C → Layer A

Now I'll summarize the solutions for all three cross-sections.

Final Answer:

Cross-Section 4:
From oldest to youngest: A → B → C → D → E → F → Fault M → G → H

Cross-Section 5:
From oldest to youngest: C → A → F → Fault B → H → Fault A → D

Cross-Section 6:
From oldest to youngest: Bottom layer → Next layer up → Next layer up → Next layer up → Feature E → Feature B → Feature C → Layer A

Note: For cross-section 6, the exact names of the layers are not provided except for A, B, C, and E. The sequence is based on the visual evidence of layer deposition and faulting/intrusion events.