Howard 等在分析加利福尼业南部海岸外的沉积相时发现了一种特别难以解释的沉积构造。在水深15至33米的沙质岩芯的 X—射线相片上清楚地表现出来的这种沉积构造可能为X—射线不能透过的重矿物颗粒,这种颗粒呈线形富集体。据作者的实验结果,Howard 等认为这种沉积构造最合理的解释为这些是重矿物富集体在穴居多毛类生物潜穴中的痕迹。在 X—射线相片上出现的未知构造主要为接近水平的略呈正弦曲线状的线条,约数 Howard et al. Found a particularly hard to interpret sedimentary structure when analyzing the sedimentary facies outside the southern coast of California. This depositional structure, clearly shown on the X-ray photographs of sandy cores at water depths of 15 to 33 meters, may be X-ray-impermeable heavy mineral particles, which are linearly enriched. According to the author’s experimental results, Howard et al. Concluded that the most reasonable explanation for this sedimentary structure is that these are the traces of heavy mineral enrichment in burrowing burrows. The unknown structures appearing on the X-ray photos are mostly nearly sinusoidal lines close to horizontal,