## 3 Analysis of Results  
### Microscopic Inspection and Analysis of Red Sandstone Specimens  
As shown in Figure 1b, according to the apparent characteristics of the red sandstone blocks sampled in the field, it can be seen that, within a certain thickness range, the red sandstone blocks can be roughly divided into three major areas, which are characterized by: the surface weathering and corrosion layer of greenish-green, containing mosses and rock debris; the intermediate layer of red and white mixed, with greater material changes and differences; and the bottom layer of the performance of the reddish-brown darker color. In the latter, we noted the appearance of characteristics that are more consistent because the location deeper, meaning it only receives small environmental impacts. Accordingly, it can be considered that this layer is in the initial stage of unweathering. In order to understand the microscopic characteristics of the red sandstone in different areas, SEM microscopic examination and XRD physical phase analysis were carried out in the above three different areas. The sampling parts are shown in Figure 3.  
Among them, Figure 4 shows the analytical results of XRD physical phase analysis, and Figure 5 shows the microelectron microscopy diagrams of Part 1 to Part 3. According to the results of SEM micro-detection as well as XRD physical phase analysis, the main substances and micro-distribution status of Part 1-Part 3 were statistically analyzed, and the statistical results are shown in Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Main Substances** & **Microscopic Distribution** \\ \hline Part 1 & Chlorite, dolomite, quartz, calcite, & Dissolved flocculent, fissure, disorderly \\  & feldspar and mica & pore distribution \\ Part 2 & Dolomite, quartz, calcite, feldspar & Broken and messy, with \\  & and mica & microscopic cracks \\ Part 3 & Quartz, calcite, feldspar and mica & Well-angled micro-grain structure, no \\  & & significant defects \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Major substances and microscopic distribution in different parts of red sandstone. Figure 3: Apparent characteristics of red sandstone specimens and microscopic detection and analysis areas. It was determined that Part 1 is the exposed region in S specimen; its microstructure has a dissolved flocculent distribution, and the cracks and pores are distributed in a messy way. The substances contained in Part 3 have more chlorite and dolomite compared to Part 2, as shown in Figures 4a and 5a. Part 2 is the gray-white region in the S specimen; its microstructure is slightly broken and messy compared to Part 3, and relatively complete compared to Part 1. In the \(\times\)1000-fold structure, the basal grain structure is found to be slightly corroded and degraded, and it contains more dolomite compared to Part 3, as shown in Figures 4b and 5b. Part 3 is the reddish sandstone red region in the S specimen, which is located in a deeper area, furthest away from the surface, and it is the part with the smallest degradation degree. The particulate structure in this area is angular, without significant cracks, fissures and other defects, and the materials contained are mostly quartz, calcite, feldspar and mica, as shown in Figures 4c and 5c. From the microstructure of the three, we determined that the structural integrity of Part 1-Part 3 increases in order, and the material of Part 1 and Part 2 changes on the basis of Part 3. Where Part 1 is the exposed surface of the specimen, the original sandy particulate structure has been in external contact with acid rain, carbonation and other environmental and anthropogenic factors, resulting in weathering and corrosion autogenous formation of chlorite material. Chlorite is a silicate mineral, commonly found in iron, that appeared in a magnesium-rich ancient water media environment.