Is the Cape Stone Forest in Shantou City formed by wave erosion? A comparison of the pedestal rocks on the coasts and the mountains of Queshi in eastern Guangdong, China

Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.

Research on Vertical Bearing Capacity of Pile Foundation under Wave Scouring

In order to analyze the influence of wave scouring on the vertical bearing behavior of the pile foundation, the finite element software ABAQUS was used to simulate the force of the pile foundation under the action of wave scouring. A three-dimensional finite element calculation model of the pile foundation was established according to the actual working conditions, and the calculation results were compared with the field test results to verify the correctness of the built model. Then, the influence of wave scouring depth and pile embedding depth on the vertical bearing behavior of pile foundation was analyzed through calculation examples. The analysis results showed that the greater the depth of wave erosion, the greater the impact on the vertical bearing behavior of the pile foundation. Meanwhile, the smaller the buried depth of the pile body, the greater the impact on the vertical bearing capacity of the pile. Thus, the reduction rate of the vertical bearing capacity under different scouring depths was obtained.

长江河口海岸演变长周期波动的初步研究

长周期波动作为一种地貌演变现象在河口海岸地区广泛存在。在长江河口。表现为长江河口水下三角洲及长江河口拦门沙地形的波动变化。而在杭州湾北岸，它又以“侵蚀波”的形式来影响岸滩的冲淤演变。本文试图通过揭示该现象内在的动力机制来综合分析其在典型河口海岸演变中的表现。同时，通过定量分析，为理论模式提供佐证。

塔里木盆地塔中30井区剖面波动过程分析

根据波动方程，７４０Ｍａ、２２０Ｍａ、１０５Ｍａ、３１Ｍａ和１０Ｍａ是控制塔中３０井区构造演化过程的主要周期，尤其是２２０Ｍａ周期控制了大地构造演化阶段．寒武纪—早志留世，该井区总体上处于快速沉降阶段；志留纪末—泥盆纪，以抬升剥蚀为主；石炭纪—二叠纪，沉积与剥蚀幅度均不大．

沉积盆地波动分析与不整合剥蚀量研究——以新疆塔里木盆地为例

沉积盆地波动分析是定量研究不整合剥蚀量的有效方法之一．该方法从地层资料入手，通过沉降史研究，恢复地层原始厚度，建立反映盆地沉积—剥蚀过程的波动方程，实现对沉积—剥蚀过程的定量预测．对新疆塔里木盆地的沉积波动分析表明，海西早期构造事件、海西末期构造事件和印支期构造事件引起的隆升剥蚀最为强烈，并以塔中隆起、塔东地区和塔北隆起造成的剥蚀量最大．

黔中隆起及周缘下组合主要不整合分布特征及其对盖层的影响

以沉积盆地沉积波动过程分析方法为理论指导,对黔中隆起及其周缘地区7个典型野外地质观测剖面震旦—石炭系沉积-剥蚀过程进行了系统分析和预测,对地层因不整合所造成的剥蚀厚度进行恢复,研究表明区内不同构造单元的沉积-剥蚀过程35Ma,20Ma的高频波动周期,定量恢复了下中奥陶统顶部、下中志留统顶部不整合剥蚀量分别为100m^540m和100m^390m。黔中隆起及周缘地区2个主要不整合呈现近西向-近北东方向和近南北向的剥蚀叠加,再现了关键时期沉降沉积区和隆起剥蚀区区域分布规律。综合分析认为不整合对盖层的影响是该区油气成藏的主要控制因素,预测盖层有利区域主要分布于黔中隆起西北部和滇黔北部坳陷。

The control of Pleistocene palaeogeography on the distribution of sandy patches in a silty Holocene lagoon(central Netherlands)

The brackish lagoon in the central part of The Netherlands was closed by a dike in 1932 and gradually changed into a lake.Parts of this lake were reclaimed and the surficial sediments of one of the polders(Noordoostpolder),reclaimed in 1942,has been investigated in detail by mapping of the walls of some1500 km of drainage ditches approx.1.4 m deep.It appeared that the sediments consist of an uncommonly large amount of silt,to different degrees mixed with reworked peat that had developed during the Holocene transgression.Some sandy deposits occur locally,at places that are at first sight distributed in a haphazard way.The various sandy patches have different characteristics(grain-size distribution,rounding of the grains,mineral composition).These sands cannot have been introduced from the sea,nor can they have been supplied by the rivers that discharged into the lagoon,so they must have a local origin.It is found that several types of Pleistocene sandy or diamictic deposits below the Holocene peat and lagoonal sediments had an irregular topography and became eroded during the Holocene by wave activity.This resulted in sandy deposits around these Pleistocene highs,which consisted of glacial tills(boulder clays),river dunes(formed by aeolian activity along rivers under dry permafrost conditions)and coversand ridges,formed by aeolian activity in a belt between the ice margin and the more distal loess belt.This finding implies that palaegeographical interpretations of local grain-size anomalies in a specific deposit should not only consider facies changes due to changes in the sediment supply,but should also consider local erosion leading to the exposure of previously deposited material with a divergent composition.