Cụ Ngựa Trắng chắc cãi nhau mệt nên đi ngủ mất rồi, cho em trả lời thay nhé:
Bằng chứng về cọc gỗ và trận Bạch Đằng năm 1288 đã được khảo cổ và phân tích có công bố năm 2011 ở đây (tài liệu tiếng Anh):
http://www.academia.edu/1152652/Understanding_the_Bach_Dang_battlefield_from_recent_research_results
Đây là kết quả nghiên cứu của nhóm Việt - Mỹ - Nhật nên chắc cụ minhlpd không nghi ngờ chứ?
Em trích 1 đoạn có kết quả phân tích đồng vị các bon 14 cho kết quả cọc gỗ có niên đại khoảng 700 năm trước (thời gian trận BĐ 1288) để các cụ khỏi mất công tìm vì nó dài lắm:
"The fishpond measured approximately 20 x 15 meters (m) and the team recorded the location of 22 visible stakes. The distribution pattern of these stakes appeared random at the time of the preliminary survey. In addition, a small trench(1m x 2m) was excavated down to a depth of approximately 3m from the surface of the fishpond. The majority of the stakes showed a remarkable state of preservation and their surfaces appeared almost new. The profile of the trench exhibited several layers indicating that a series of depositional events took placein the past. The soil profile was characterized with a deep deposit of clayoverlaying a deposit of sand, which indicates a typical estuary or a shallow river gradually filling in. Considering the well-preserved nature of the wood, recentdepositional events may have occurred at a relatively fast pace (Lê et al. 2009;Sasaki 2009).
One of the principal research questions for this project has been to establish accurate dates for the stake yards, which involves a program of radiocarbon dating of samples from the stakes. Five wood samples from isolated stakes were collected for Carbon 14 (C14) analysis and species identification.The results of C14 analysis provided a date range around 700 years Before Present (BP) that was in accordance with our expectations."