The deep and wide holes endangering the two Croatian villages are known as cover-collapse sinkholes. They usually appear in areas where the underground rock has been hollowed out to form cavities and caves by water and is covered with a thick layer of soil, sand or alluvium, and most importantly, clay.
อ่านต่อเพิ่มเติม โรงเรียนบ้านนาเส
สาระสำคัญ แรงงาน