The physical properties of sediments at Site 1250, located east of the carbonate pinnacle, are similar to those at Site 1249. At Site 1250, three holes (Holes 1250C, 1250D, and 1250F) were used for physical property analyses. Standard sampling and measurement procedures were applied as outlined in "Physical Properties" in the "Explanatory Notes" chapter. Core recovery was generally good, and only a few data gaps are present.
In all holes cored at this site, a downhole profile of IR temperature was acquired and was used for on-catwalk hydrate detection. Twenty samples, which were thought to be hydrate, were taken on the catwalk; however, the IR images show a much higher number of cold-spot anomalies, which we interpret to indicate additional instances of the presence of hydrate.
IR imaging of cores recovered at Site 1250 enabled the on-catwalk identification of hydrate zones in each core, as described in "Physical Properties" in the "Explanatory Notes" chapter. This information was used to facilitate hydrate sampling and preservation for all cores. The IR thermal anomalies are cataloged in Table T12, which includes an interpretation of the overall hydrate texture for each anomaly. A large fraction (60%) of the anomalies in both Holes 1250C and 1250D are apparently created by disseminated hydrate. Vein-filled features account for 25%-28%, and nodular features account for 12%-14% of the hydrate associated with the IR anomalies. No trends with depth were identified for these three types of anomalies. The abundance of disseminated hydrate and veins or lenses parallel to bedding suggests that stratigraphy exerts a significant control on the occurrence of gas hydrate at this site.
Successive thermal images were used to produce downcore thermal profiles for each core recovered in Holes 1250C and 1250D (Fig. F23). Extensive cold anomalies are present between 14 and 109 mbsf in Hole 1250C and between 6 and 113 mbsf in Hole 1250D, which is consistent with a BSR depth of 112 mbsf. The temperature anomalies created by hydrate have been extracted from the downcore temperature data and from direct examination of IR images (Fig. F24). Comparison of anomalies from Holes 1250C and 1250D indicates significant differences between the two holes (separated by 40 m, 20 m north and south of Hole 1250A, respectively) (Fig. F1). Overall downcore trends are similar, but Hole 1250D has more anomalies than Hole 1250C (57 vs. 40 anomalies). Most of the anomalies present in Hole 1250D are small 
Ts, but there is no obvious bias in the detection of anomalies. Larger T s are present in Hole 1250C. The opposite would be expected if, for some reason, thermal anomalies were detected less effectively in Hole 1250C. Core recovery plots (Fig. F24) show that poor core recovery in the upper part of both holes limited detection of shallow hydrate if present.
Comparison of pore water saturation (Sw) calculated from LWD (see Fig. F42) with thermal anomalies shows a generally good correlation between the two methods of hydrate detection. However, Sw estimates suggest increasing hydrate concentration approaching the BSR (112 mbsf). IR anomalies show peak hydrate presence at ~45-80 mbsf. Comparison with wireline logging results in Hole 1250F may help to determine if this discrepancy represents heterogeneity in the presence of hydrate on a scale of 25 m horizontally or if the combined uncertainty in IR anomalies and resistivity logging data are responsible for hole-to-hole differences.
Overall data trends in sediment density at Site 1250 are related to the normal compaction gradient of the sediments (Fig. F25). Densities are ~1.6 g/cm3 at the seafloor and increase to ~1.8 g/cm3 at 150 mbsf at the BOH (Table T13). There is a distinct density change at 45 mbsf that correlates to seismic Horizon Y (Fig. F26). Density increases by ~0.15 g/cm3, and porosity decreases by ~10%. There is one distinct outlier in the moisture and density (MAD) bulk density data at a depth of 40.72 mbsf with a density of 2.033 g/cm3. This data point corresponds to a sample taken in a sandy layer (Sample 204-1250C-5H-6, 30-32 cm), which is within the interval of turbidites that are present around Horizon Y (Fig. F27B). An equivalent sample from a sandy layer was taken at a depth of 133.92 mbsf (Sample 204-1250C-17H-2, 42-44 cm) with a density of 1.949 g/cm3 (Fig. F27A). The sandy layers have a lower water content than the surrounding clay-rich sediments. The MAD measurements are mass-property measurements (see "Physical Properties" in the "Explanatory Notes" chapter), and the clay-rich sediments, therefore, show a lower density than the sandy layers. The sandy layers have higher bulk density and lower porosity than the clays in the MAD data. The MAD data differ from the gamma ray attenuation (GRA) measurements by ~0.2 g/cm3 for unknown reasons.
Five PCS cores were successfully taken at this site. These were available for physical property analyses (Cores 204-1250C-16P; 204-1250D-5P, 13P, and 18P; and 204-1250F-4P). Generally, three MAD samples are taken from each PCS core. There is an apparent mismatch with the general downhole trend in bulk density and the values obtained from the PCS core samples. The density in Core 204-1250D-13P is higher than the background trend, whereas densities from Cores 18P and 204-1250C-16P are much lower. Densities derived from Core 204-1250D-5P are within the general trend. There is no change in lithology between the PCS and adjacent APC/XCB cores that could explain the observed difference in bulk density. There was also no special procedure applied to the PCS sediments to measure bulk density. A possible explanation may be the treatment of the PCS prior to MAD analyses or in the way the cores were obtained in situ compared to regular APC/XCB coring. Specifically, PCS sediments are depressurized slowly compared to APC/XCB, and PCS sediments are extruded from the PCS barrel using water pressure.
At Site 1250, seismic Horizon A was cored at ~150 mbsf. The LWD data indicate a prominent drop in sediment density by >0.4 g/cm3. There is no equivalent drop detected in the MAD and GRA data. Individual samples taken from cores follow the main background trend, except for a few samples showing higher bulk densities, which are correlated with sandy intervals. A sample taken directly at the top of interval 204-1250F-10X-4, 1-3 cm, which is an interval with a very high ash content (Fig. F27C), shows a bulk density from the MAD analyses of 1.79 g/cm3 and a grain density of 2.62 g/cm3 (indication of the ash content).
MS appears relatively uniform at Site 1250 (Fig. F26), with values generally <40 x 10-7 (SI). Several small-scale spikes appear in the MS data and are either associated with the presence of abundant authigenic sulfides or turbidite layers. An MS anomaly in Core 204-1250C-8H is associated with a single sulfide spot (Fig. F28). The sulfide precipitate has a diameter of <1 cm but results in an anomaly that is spread out over >5 cm, which is a function of the spatial resolution of the loop sensor with the core diameter used.
An example of stratigraphically controlled MS anomalies can be found at ~42-44 mbsf (Fig. F29). This MS anomaly is near seismic Horizon Y (see "Lithostratigraphy"). The expanded MS section and core photographs illustrate typical peaks in the record caused by magnetically susceptible minerals in the turbidites.
No velocity measurements were carried out at Site 1250 as a result of poor core recovery and intensive gas-expansion cracks.
Thermal conductivity was measured in Holes 1250C and 1250D. The three measurements at Hole 1250E are relatively low and might have been affected by gas expansion (Table T14). No distinct downhole trend was observed, and thermal conductivity is, on average, 0.967 W/(m·K).
No shear strength measurements were carried out at Site 1250 because of poor core recovery and/or abundant gas-expansion cracks.
At Site 1250, physical properties agree well with the description of the lithostratigraphic units. The boundary between lithostratigraphic Units II and III is present at a depth of 45 mbsf and is correlated with seismic Horizon Y. This horizon is interpreted as an unconformity based on observed changes in lithologic and seismic characteristics, such as a relatively sharp increase in sediment density. This is best seen in LWD and GRA density data from Hole 1250D, which had better core recovery than Hole 1250C.
The prominent seismic Horizon A was not cored in Holes 1250C and 1250D but was drilled during the LWD program (Hole 1250A) and during the revisit to Hole 1250F. There is a discrepancy between the LWD data and the laboratory density measurements. The LWD, which measured in situ properties, detects a prominent drop in sediment density, whereas no similar effect is seen in the MAD and GRA data. This discrepancy was detected in all cores from the different sites where Horizon A was cored and is thought to indicate the presence of gas in situ in Horizon A.
IR imaging provided the best method for on-catwalk detection of hydrate. At Site 1250, 20 hydrate samples were collected; however, there is considerable mismatch between the Sw calculated from the LWD resistivity data and the temperature anomalies in the IR images.
