caused by 在SAT语法中正确么

caused by 在SAT语法中正确么
caused by 正确么 例如：In Alaska, the ground is riddled with ice wedges, many quite ancient, caused by the cold earth cracks and the cracks fill with water. 答案是改成when the cold earth cracks.那么是因为caused by在任何剧中都不对还是只在这个结构里. 另外 修饰动词是用more + 副词 对否