Chapter 3: Thermal Gradient

When working in the upper crust the maximum thermal gradient is generally assumed to be vertical. Direct measurement of underground temperature requires that a temperature-measuring device be lowered down a borehole. For the deep oceans, instruments take the form of thermistor-lined probes that penetrate the soft sediment on the sea floor. Near-surface temperature profiles record changes in surface temperature as deviations from equilibrium gradients. These deviations can be inverted to reconstruct the recent climatic history of the region.


Colour versions of some of the figures from Chapter 3. Click on the figure for a larger version.

figure 3.4 cut away

Figure 3.4. A cut-away view of a Bullard-type heat flow probe, showing thermistors positioned in contact with the steel casing. Thermistors are generally spaced about 25cm apart.

figure 3.5 cut away

Figure 3.5. A cut-away view of a Ewing-type heat flow probe. Thermistor spacing is usually about 25cm.

figure 3.6 cut away lister

Figure 3.6. A cut-away view of a Lister ‘violin bow’ heat flow probe (Horizontal scale expanded on inset).

figure 3.12 average sea surface temperature model

Figure 3.12. Average sea surface temperature model (C). Modified after Boville and Gent(1998).

Reference List