What is the "crossing the gorge" in the geomantic omen of Yin House?

What is the "crossing the gorge" in the geomantic omen of Yin House? Between the two peaks, there should be a mountain. From a distance, there is a faint slightly raised line, just like a long worm crawling, connecting the two mountains, which is called "Dragon Crossing the Gorge" in geomantic omen. There is a slight bump, just like a long bug crawling on a line. If there are natural ponds and swamps on both sides, it is the best "living dragon crossing the gorge".