Due to the shallow bedrock and large amount of incoming sand, the Pearl River Delta stretches rapidly to the sea, making Panyu, Zhuhai and Doumen become counties and cities with more fields. The coastline keeps stretching to the sea. The delta was formed about 6 years ago in the Atlantic period. At that time, the coastline could be determined by the coastal topography at the foot of hills and slopes in the delta, such as sea cliffs, sea caves, sea platforms and sand dikes. Today, these coastal landforms can be seen at the foot of the hills in the delta plain, such as the marine cliff and marine platform in Qixinggang, Guangzhou. Therefore, the coastline of Shuigu Bay in Guangzhou can basically be determined by the contact line between hills and plains. Delta began to develop at these coastal geomorphological fronts, such as the plain in the lower reaches of Xijiang River, which extended to the vicinity of Guangli, because the age of Shell Island Beiqiu and the Neolithic site buried in Qujiao was 717 14 years, while the pottery was 568 284 years (thermoluminescence), and the Beiqiu in Boluo Hulushan was also on the plain, which means that the deltas in the lower reaches of the rivers have developed. According to the distribution of marine diatoms (saltwater species), foraminifera and silt layers, the delta areas in the lower reaches of each river basically reflect the scope of transgression in the Atlantic period, that is, the coastline 6 years ago reaches Qingyuan Basin in the north, Zhaoqing Basin in the west (Zhao Huanting, 199), Boluo Basin in the east and Tonghu Lake in the east.

judging from the Neolithic sites, the Neolithic sites can basically be used as the coastline in the Dongjiang Delta. Because there are no rocky islands in the middle of the Dongjiang Delta, most of them are still on the sea surface, so the four neighbors of the Dongjiang Delta are the Neolithic coastline around 4 years. The top of the Northwest River Delta has also begun to take shape. Because the site of the dry fence on the water in Jinlimaogang is 414 9 years (C14 measurement), the rotten wood layer is 397 11 years (Geomorphology Room of South China Normal University, 1988), and the age of Xiqiao Mountain Beiqiu is from 612 13 years (ditto) to 495 1 years, more than 53, stone tools have been unearthed. The age of the epiphytic blue clam under the cliff in Shijie, South China Sea is also 464 28 years. That is, the northwest river delta has reached the south of Xiqiao Mountain and Foshan line (the silt of rattan is 3997 19 years).

before p>2 (Qin and Han dynasties), the Dongjiang Delta was merged from Dongjiang Delta and Zengjiang Delta, and extended to nave (with Yingtang Temple in Han Dynasty), and the south was still a sea area. The northwest river delta extends northeast to the north of the South China Waterway (that is, the East China Sea Waterway). Because the cultural relics such as pottery pieces of Han Dynasty have been found in Xingtan, the burial depth is 2m (fengjian village). The freshwater Malay crocodile has been growing in Leliu for 254 12 years. Shichong is the hometown of Lvjia, the south Vietnamese phase, so its vicinity should be a plain. Chencun has also become a land in the Han Dynasty.

1 years ago (Tang Dynasty), the Dongjiang River had reached Dongguan City, that is, the top of the Dongjiang River Delta had developed. But most of them are still pearl ponds. The top of Panyu thrust delta has been developed, because the "Yuanhe County Records" says that "Guangzhou is due south to the sea for 7 miles", which shows that the land is right between Shawan and Shunde. The top of Zhongshan thrust delta has also developed, because Huang Chao has been stationed in Rongqi, Guizhou and Maqi today, so it can be seen that the nearby area has become the hometown of large paddy fields. Xinhui thrust delta also has a top plain, such as Xinhui, which is the seat of the Sui Dynasty, indicating that a large plain had been formed at that time. The strata in the Tang Dynasty mostly covered the strata in the Han Dynasty, and the delta coastline did not advance much during the Millennium of the Han and Tang Dynasties, which may be related to the rising sea level in this period.

7 years ago (at the end of the Song Dynasty), the coastline went south to the central part of each thrust delta, and the Dongjiang River reached the line of Mayong, Dafen and Daojiao (according to the genealogy); Panyu has reached the front line of nuclear and fish vortex, and Xiqiaoyong has been recorded (1233); Zhongshan coastline is in the first line of Henglan, Fuwei (now named Fusha), Huangpu and Tanzhou (according to records); Near Xinhui, the Song Dynasty has become a tidal field, and the ritual and music have become sand in the open sea. Tanjiang River developed rapidly in this period, with Gemini and Huang Chong as the first line, which was the result of the influx of immigrants from Zhuji Port into the delta to build dikes in the Song Dynasty. Changing tidal fields into flat fields also had an impact on sea level decline. Jiaowei is a waterway connecting the two rivers.

4 years ago (at the end of Ming Dynasty), due to the dike construction in Song Dynasty, all the eroded deltas accelerated the deposition of sand. For example, Zhongshan belonged to Dongguan in the early Song Dynasty, and it began to enter Guangzhou in the Southern Song Dynasty. Because Xiangshan and Panyu were three hundred miles across the sea in the Northern Song Dynasty, it was better to go to Dongguan. This shows that in the Southern Song Dynasty, the Zhongshan thrust delta has extended to Shiqi and Gangkou, that is, the Sixteen Sands in the East China Sea and the Eighteen Sands in the West Sea have been formed. Panyu thrust delta has reached Xiahengli (Yisha), and Hongqilikou Gate has taken shape. Xinhui thrust delta has reached Jiuzisha in the southern margin, and the coastline has moved from Lile to Xiongzishan (that is, Xiongzhou). Most of the Dongjiang Delta was formed in the late Song Dynasty. In the late Ming Dynasty, it extended to the east of Zhangpeng, and the south tributary also extended to the north of Houjie. In the Ming Dynasty, the acceleration of the delta coastline was also artificially influenced. In the Ming Dynasty, instead of building dikes to protect fields as in the Song Dynasty, dikes were built into fields, and reeds and grasses were planted on the beach to promote siltation. The top of Doumen Delta has begun to develop, that is, the Great Aosha has been formed, and Muzhou and Sanjiangkou have also risen. Yellow cloth and big sand have become, and they only enter the island in the south of Zhuzhou and Fenzhou.

1 years ago (in the late Qing Dynasty), the coastline was pushed forward again, and the outer edge of the delta was cut off at Doumen, that is, bamboo was used to expel sand, lanterns were used to sand the east side and west side; Xinhui will go to the bank of Yinzhou Lake in the west of Sanjiang Xu, and the coastline of Panyu will fill up the Wuzhu Ocean, and the thousands of hectares of sand have reached ten surges. Dongjiang is progressing slowly, because the lion ocean has strong tides.

In short, the coastline of the Pearl River Delta is constantly moving towards the sea, and there are fast and slow periods, which are related to the fluctuation of sea level in natural factors. In the high sea level period, the coastline advances slowly, while in the low sea level period, it is faster. Man-made factors are embankment construction, such as embankment protection in Song Dynasty, which accelerated the sedimentation in the downstream Shatian, and embankment construction and planting reed mud in Ming Dynasty, which accelerated the sedimentation. Tidal action and upstream sediment and water also have an impact, such as the slow siltation in Humen and Yamen waterways, which is why the tidal current is strong. In the delta area between Humen and Yamen, siltation is strengthened.