Archive halves of 27 of the 58 RCB sections recovered (excluding core catchers) at Site 1097 were measured using a 5-cm measurement interval (Fig. F16). From Core 178-1097A-17R to the bottom of the hole, the sensor velocity was decreased from 15 to 10 cm/s to avoid saturation of the magnetometer electronics. This saturation results from high variations of the magnetic flux (flux jumps) induced by the rapid motion of highly magnetized material past the sensor. Sections of cores containing pebbles and cobbles (dropstones or rocks from glacial units) were not measured because their magnetization is unrelated to the ambient geomagnetic field at the time of deposition and cannot be used for constructing a magnetostratigraphic record. In addition, many dropstones have a very high intensity of magnetization, which causes flux jumps in the cryogenic magnetometer.

Measurement of discrete samples from the working halves of cores and subsequent data analysis followed the methods described in "Paleomagnetism" in the "Site 1095" chapter. Stepwise alternating field (AF) demagnetization of samples revealed that the drill-string overprint was dominantly vertically downward, showing the same behavior as that observed at Site 1095 (see "Paleomagnetism" in the "Site 1095" chapter). The drill-string overprint was mostly or wholly removed by partial AF demagnetization of the natural remanent magnetization (NRM) at the 10-mT level. Of the 28 samples measured (Fig. F16), 12 had no stable direction of magnetization (Fig. F17). These samples are mainly from Cores 178-1097A-10R through 18R and 40R through 44R, which were identified as diamicts (See "Lithostratigraphy"). The magnetization in the diamicts appears to be controlled by coarse-grained magnetic minerals (>10 µm for magnetite), which are inherently poor magnetic recorders and typically give no stable magnetization direction.

Within a multidomain grain (>10 µm for magnetite), the magnetic moments organize into many regions such that the vector sum of all the moments, and hence the magnetostatic energy, is minimized. This inherent property of multidomain magnetic minerals precludes their recording a depositional remanence. A depositional remanence is acquired through the torque exerted by the Earth's magnetic field on the magnetization of a magnetic mineral. Large multidomain grains whose magnetization is extremely small experience a very weak torque, which is not sufficient to overcome gravitational effects and align the grain's magnetization with the geomagnetic field.

Stable directions were found in the finer grained intervals of Cores 178-1097A-19R through 28R, 34R through 39R, and 45R through 46R. Of the 16 samples with stable directions, eight had weak intensities and dropped into the noise level of the cryogenic magnetometer at the 40- or 50-mT AF demagnetization step. These directions were only stable between 10 and 40 mT and typically had a shallow inclination, which is inconsistent with what is expected for a high-latitude site (Fig. F18). Two of these samples, 178-1097A-27R-1, 34 cm, and 17R-1, 69 cm, were taken from sediments that were identified as a debris flow and a weakly stratified deformation till, respectively (see "Lithostratigraphy"). The shallow inclinations observed in these samples could be the result of the depositional process and may not reflect the geomagnetic field direction. Only eight of the 28 subsamples had strong intensities and steep inclinations. These samples came from ice-proximal glacial marine lithologies (Fig. F19) (see "Lithostratigraphy").

Several complications make the construction of a magnetostratigraphy impossible. First, the nature of deposition of diamicts, the main lithology (see "Lithostratigraphy"), is probably erratic instead of continuous through time. Second, it is unclear how a diamict would acquire a depositional remanence: deposition of magnetic particles within a diamict unit should be controlled by ice flow and gravity flows within the massive unit, instead of orientation of particles by the geomagnetic field as they fall through the water column (the standard depositional remanence mechanism).

Finer grained lithologies (silty clays instead of diamicts) at Site 1097 give stable paleomagnetic results, but the occurrences of these lithologies were sparse. A hiatus between each change in lithology is possible, with the time gap possibly being significant relative to the length of geomagnetic reversals. A more severe interpretation limitation comes from the large gaps in recovery. The gaps are 1-10 times the size of the recovered intervals. A smaller problem is that the position of the recovered core is also not known within the cored interval. Cores 178-1097A-10R though 46R may give a sequence of normal and reversed polarities, but this oversimplified interpretation ignores the complications discussed above. Furthermore, even with a short sequence of reversals in an undated stratigraphic section with unknown sedimentation rates, a unique interpretation is impossible. The erratic nature of deposition on the continental shelf, the inability of coarse-grained magnetic minerals (common in diamicts and diamictites) to record the paleomagnetic field, the lack of age constraints, and sparse recovery all prevent construction of a meaningful magnetostratigraphy.