Baanthonglaanglai farm is in Lat Bua Luang district of Phra Nakhon Si Ayutthaya province in the central plain region of Chao Phraya river basin. The name “Lat Bua Luang” in Thai means “Swamp of Sacred Lotus”, indicating native flora often found in the area. It has been almost three years since I started the dream project to convert monocrop of rice field into agroforestry. I think I should start observing and taking notes on flora and fauna succession during the early phase of the project between May 2016 and April 2019.
Having looked at the geological reports related to the site, I came across the literature on the soil in the southernmost of Chao Phraya river basin, the Bangkok Clay, published in 1983 by Chonglakmani and co-workers. The fossil oyster shell of the length of 30 – 40 cm found within the depth around 3 – 4 meters during the excavation could be the Crassosterea gigas. This species is commonly found in Bangkok Clay within the depth of 3 to 7 meters below ground level, similar species as the famous fossil at Wat Chedi Hoi (วัดเจดีย์หอย) 30 kilometers away. The carbon dating cited in the literature suggested the sedimentation compact of 5,500 years before present.
For those who are interested in geological information of Bangkok Clay (soft marine clay deposited where Chao Phraya river interacted with marine process as a sea-level change during Holocene epoch):
Chonglakmani, C. Ingavat, R., Piccoli, G. and Robba, E. 1983. The last marine submersion of the Bangkok area in Thailand. Memorie Di Scienze Geologiche. Padova, v.XXXVI, 343 – 352.
Teerachaikulpanich, N. and Phupat, V. 2003. Geological and geotechnical engineering properties of Bangkok Clay. https://www.jstage.jst.go.jp/article/jiban/JGS38/0/JGS38_0_143/_pdf/-char/ja accessed 12 April 2019.