## 4 Results
### Drilling Profiles
#### 4.2.3 Marker Layers and Fault Analysis  
As mentioned above, the age constraints of the loess-paleosol layers in the drilling profiles relied on a previously established chronological scale; the top and boundary ages of the paleosol layers S0-S5 are listed in Table 1.  
In drilling profile A-A\({}^{\prime}\), the main marker layers that exhibit relatively stable, continuous thickness and distinct color are layers 2, 4, 6, 8 and 9. Layers 2, 4, 6 and 8 correspond to the eolian paleosol S1-S4, while layer 6 represents a silty clay layer deposited in a fluvial-lacustrine environment. Similarly, in the drilling profile B-B\({}^{\prime}\), marker layers 3 and 5 correspond to the S1-S2 paleosol, while layer 7 is the silty clay layer. Among them, the paleosol S1 (layer 2 in profile A-A\({}^{\prime}\), layer 3 in profile B-B\({}^{\prime}\)) and the silty clay layer (layer 6 in profile A-A\({}^{\prime}\), layer 2 in profile B-B\({}^{\prime}\)) are most helpful to identify the Late Pleistocene activity and location of the Wangjiabian-Houjiawan Fault (F1-1a). The paleosol S1 can be further divided into four sub-layers (Figure 5b). There is a thin light-colored layer at the top (i), followed by a reddish-brown layer containing lots of white calcareous streaks (ii). Layer (iii) has a lighter reddish-brown color with less calcareous streaks, and a calcareous concretion layer (iv) is at the bottom. Paleosol S1 was found in most boreholes, with the exception of ZK14, where it was excavated before drilling. The extension trend in each marker layer in profile A-A\({}^{\prime}\) shows a clear change in the slope between ZK3 and ZK9, indicating the presence of a fault. Marker layers 4, 5, 8 and 9 are faulted, and their respective displacements are shown in Table 2. The marker layer 2 shows continuous extension without any noticeable vertical displacement, which means that the fault does not extend upwards into layer 2. The depth variations in marker layer 2 in profile B-B\({}^{\prime}\) suggest the existence of a fault between ZK13 and ZK15, with a vertical displacement of 12 m at the top boundary. The slope of marker layers 3 and 5 exhibits slight variations in the drilling profile, possibly due to the non-linear alignment of the boreholes. In general, it is difficult to distinguish the displacement presented in marker layers 3 and 5. In summary, the drilling profiles reveal that the Wangjiabian-Houjiawan Fault (F1-1a) is located between boreholes ZK3 and ZK9 in profile A-A\({}^{\prime}\), and between boreholes ZK13 and ZK15 in profile B-B\({}^{\prime}\). The fault strikes -79\({}^{\circ}\) in the study area, and coincides with the scarp. The buried depth of the fault up-breakpoint is close to 15 m. The fault was active in \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Marker Layer** & **Layer** & \
\begin{tabular}{c} **Elevation of** \\ **the Football/m** \\ \end{tabular} &
\begin{tabular}{c} **Elevation of the** \\ **Hanging Wall/m** \\ \end{tabular} & **Displacement/m** \\ \hline Profile A–A\({}^{\prime}\): layer 4 top & Paleosol S2 & 480.68–488.12 & 455.16–473.18 & 2.5 \\ Profile B–B\({}^{\prime}\): layer 5 top & Paleosol S4 & 484.11–508.63 & 470.51–474.70 & - \\ \hline Profile A-A\({}^{\prime}\): layer 4 bottom & Paleosol S2 & 478.98–484.02 & 453.36–469.28 & 2.5 \\ Profile B–B\({}^{\prime}\): layer 5 bottom & Paleosol S2 & 479.91–504.63 & 466.71–470.50 & - \\ \hline Profile A–A\({}^{\prime}\): layer 6 top & Paleosol S3 & 471.68–479.72 & 444.46–464.78 & 2.5 \\ \hline Profile A-A\({}^{\prime}\): layer 6 bottom & Paleosol S3 & 469.88–476.72 & 442.56–461.58 & 3.5 \\ \hline Profile A–A\({}^{\prime}\): layer 6 top & Paleosol S4 & 465.58–472.12 & 437.26–457.88 & 3.5 \\ \hline Profile A–A\({}^{\prime}\): layer 6 bottom & Paleosol S4 & 463.76–470.02 & 434.96–455.68 & 3.5 \\ \hline Profile A–A\({}^{\prime}\): layer 6 top & Silty clay & 387.72–392.00 & 373.28–378.56 & 20 \\ Profile B–B\({}^{\prime}\): layer 9 top & 390.53–401.83 & 381.71–383.70 & 12 \\ \hline \hline \end{tabular}
\end{table}