# deltametrics.strat.compute_thickness_surfaces¶

deltametrics.strat.compute_thickness_surfaces(top_surface, bottom_surface)

Compute deposit thickness.

This computation determines the deposit thickness, based on two bounding surfaces. It is a calculation of `(top_surface - bottom_surface)`, with corrections to invalidate areas of no-deposition or net erosion, i.e., hightlighting only where net deposition has occurred.

Note

This function does not operate directly on `StratigraphyCube`, but on two surfaces of interest (which could be extracted from a `StratigraphyCube`). See example.

Parameters:
• top_surface – Elevation of top-bounding surface for computation. This is often the air-sediment surface, or an isochron surface in stratigraphy.

• bottom_surface – Elevation of bottom-bounding surface for computation. This is often the pre-deposition basin surface.

Returns:

difference – Difference in elevation between `top_surface` and `bottom_surface`.

Return type:

`ndarray` or `DataArray`

Examples

```golfcube = dm.sample_data.golf()
deposit_thickness0 = dm.strat.compute_thickness_surfaces(
golfcube['eta'][-1, :, :],
golfcube['eta'][0, :, :])
deposit_thickness1 = dm.strat.compute_thickness_surfaces(
golfcube['eta'][-1, :, :],
np.min(golfcube['eta'], axis=0))

fig, ax = plt.subplots(1, 2)
im = ax[0].imshow(deposit_thickness0)
dm.plot.append_colorbar(im, ax=ax[0])
ax[0].set_title('thickness above initial basin')
im = ax[1].imshow(deposit_thickness1)
dm.plot.append_colorbar(im, ax=ax[1])
ax[1].set_title('total deposit thickness')
plt.tight_layout()
plt.show()
```