Your guesses are understandable but incorrect in this context. Let’s break it down:
1. “Travelled or perched blocks” does not refer to people. Instead, it refers to large rocks or boulders that have been moved by glaciers and then left in a new location. These are often called “glacial erratics” in geology.
2. “Blocks” here refers to physical rocks or boulders, not people.
Explanation:
• “Travelled blocks” → Rocks that have been moved from their original location by glacial movement.
• “Perched blocks” → Rocks that are left in an unusual position, often balanced on top of another surface after the glacier melts.
Correct Understanding of the Sentence:
“The phenomenon of travelled or perched blocks is also a common one in all glacier countries.”
(The occurrence of rocks that have been moved or left in strange positions by glaciers is common in all countries with glaciers.)