With the accumulations of outcomes from archaeological excavations of mountain fortress of three kingdoms period, there have been studies about time-periodic territory range of mountain fortress, difference in the way(method) of construction, defence system and so on from various points of view. This is an empirical study on the construction method of the valley part of stone fortress. First of all, it is required to secure large quantity of fresh water for those who lived at mountain fortress. Especially when builders of fortress construct a fortification at the valley part of stone fortress, in advance they must sufficiently consider several options including the establishment of sustainable water resources. First, when it comes to build a fortification on a ridge[or a slope] of a mountain, you have only to consider a vertical stress. However, when it comes to build a fortification at the valley part of a mountain, You must have more sufficient preparations for the constructing process. Because there are not only a vertical stress but also a horizontal pressure simultaneously. Second, a fortification of mountain fortress built by using unit building stone is a structure of masonry construction like brick construction, and the valley part of it is where the construction of the fortification begins. Third, when it comes to build a fortification at the valley part of a mountain, it seems that they use a temporary method such as coffer dam in oder to prevent the collapse of the fortification due to heavy rain. Furthermore, in response to a horizontal pressure a fortification is built by the way of its plane make an arch, or by piling up the soil with the plate method(類似版築) and earthen wall harder method(敷葉) they increase cross-sectional area of the fortification and its cutoff capacity. In front direction they put the reservoir facility for the fear that the hydraulic pressure and earth pressure are directly transmitted to the fortification. The process of constructing the fortification at the valley part of a mountain is done in the same oder as follows; leveling of ground(整地) ⇨ construction of coffer dam ⇨ construction of the fortification between the both banks of the valley ⇨ construction of the fortification at bottom part of spill way(餘水路) between the both banks of the valley ⇨ construction of spill way(餘水路) & reservoir facility ⇨ construction of the fortification at upper part of spill way between the both banks of the valley. Coffer dam facility seems to be not only the protection device on occasion of flood but also an important criterion to measure the proper height of spill way or tailrace(放水路). This study has a meaningful significance in that it empirically examines the method of reduction of the horizontal pressure which the fortification at the valley part of a mountain takes, the date the construction was done, and wether the changes in climate such as heavy rainfall influence the process of construction.

The purpose of this study is to clarify the environmental changes and human activities before and after the fortification of the Seongsan Sanseong Fortress (hereinafter mountain fortress) in Haman through using pollen analysis. For this purpose, samples were taken at the Tr-2 site in the Warm-temperate forest. The results of the analysis are as follow. ① Before and after the fortification of the mountain fortress, the area around it has changed from a broad-leaved forest (The HS-I period) into a deciduous broad-leaved forest (The HS-II period) and finally into a the mixed conifer and deciduous broad-leaved forest (The HS-III period). ② The HS-I period (before the middle of the 6th century, compared to the nationwide pollen zone RIIIa during the Postglacial) was covered with cool-temperate southern forests(including some species of Warm-temperate trees) and was very similar to the current climate environment during the Gaya period before the fortification. ③ The HS-II period (mid to late 6th century, pollen zone RIIIa) was covered with typical cool-temperate southern forests after the fortification and the temperature was slightly lower than the first stage. ④ The HS-III period (7th~8th century/9th century, pollen zone RIIIb) is an era of clear human interference, causing the destruction of forests in earnest and paving an active agricultural life.