## 4 Results Interpretation and Drilling Verification
### Drilling Verification  
According to the comprehensive exploration interpretation results in the previous section, drilling verification is carried out on sk09 and sk10 in Figures 1 and 2, respectively. The final hole depth of sk09 is 202.18 m (Figure 5), and that of sk10 is 302.8 m (Figure 6). For sk09, over 89.5 m below the surface is Quaternary, and 3.7 m above is cultivated soil, silty clay is at 3.7 m-18.3 m, and a sandy pebble layer is located between 18.3 m and 89.5 m. The silty shales of the Ordovician Basihuxi formation are at 89.5 m-147.8 m, and the dolomitic limestone of the Cambrian Tanxi formation is located at 147.8 m-202.18 m. For sk10, 9.7 m below the surface is the reticular clay of the middle Pleistocene Mawangdui formation, a Quaternary Holocene gravel layer is located from 9.7 m to 71.52 m below the surface, and a Cretaceous red bed is located 71.52 m-275.74 m below the surface. Below 275.74 m, it is the crystalline argillaceous limestone of the Cambrian Wunidtang formation.  
Figure 4: Lithographic layering results of sk10 natural source surface wave microtremor detection of dispersive wave velocity.  
The drilling results correspond well with the microtremor detection results, especially the inner stratification of low resistivity Quaternary and Cretaceous red beds, which prove to be accurate.  
Figure 5: sk9 drilling core cataloguing results.  
71.52-142.55m: calcareousus silty mudstone, brick red - brownish red colored, medium wearhered - unweathered, the core is relatively complete, the fissure is not developed, basically containing no water.  
142.55-148.30m: argilaceous silistone, brownish red, unweathered; stratified structure, elastic texture, developped fracture with poor pore water.  
148.30-167.10m: fine sandstone, brownish red, unweathered, massive structure, elastic texture, developped fracture with poor pore water.  
167.10-238.46m: calc-argillaceous silistone, brownish red, unweathered, stratified structure, peliti texture; complete core in long column shape, the fissure is not developed, basically containing no water 238.46-242.50m: fine sandstone, light red, calcium cementing, developed fissures; the core is broken into pieces, stratified structure, elastic texture, developped fracture with poor pore water.  
242.50-275.54m: calcium silty mudstone, brick red - brownish red, light red colored, stratified structure, pelititic texture; complete core in long column shape, the fissure is not developed, basically containing no water water.  
275.74-219.7  
Banded anrollatone, dark grey bands alternated with grayish white ones, interbeded with mudstone; stratified structure, pelititic texture; the bands are crumpled and curved, the fissures are argillaceous filled; in 285.20-290.00m, the cores are crushed, mostly mechanical broken, almost without water.  
Banded argillaceous limestone, unpunched, light grey-dark grey, stratified structure, mieritic texture; the core is 50% broken and shown in fragmented shape, the rest are long-short columnar shape; karst is not developed, and the fractures are developed along the bedding plane; the fractures are mostly filled with calcite veins, small dissolved pores are developed around the calcite, containing poor pore water.