Thoughts:

A dolmen, an ancient architectural structure, typically comprises two or more upright megaliths supporting a large, flat horizontal capstone. These structures have been found across the world, yet their origins—when, why, and by whom the earliest dolmens were constructed—remain unclear. The oldest known artifacts of this type, dating back approximately 7,000 years ago, are discovered in Western Europe. It's remarkable how our ancestors crafted these structures to achieve equilibrium, making them a perfect example in statics and fundamental mechanics.

Thoughts:

If you have much experience for the fracture behavior of different structures, such as adhesively-bonded joints, fiber-reinforced polymers, and others. You probably can tell immediately that this ice load was under global shear (Mode II), and the fracture pattern with discontinuous, inclined cracks was caused by local maximum principal stress (Mode I).

People may ask why ice, which is considered brittle, fractured in this manner. Should it fracture differently than, for example, the fiber-reinforced polymer composites I mentioned earlier? If you are familiar with quasi-brittle fracture mechanics, you will know that ice is also a quasi-brittle material, like polymer composites.