Typo fix in: Update 16_mass_conserving.md

doc/sphinx/user_manual/basic_starter_tutorial/16_mass_conserving.md

@@ -2,7 +2,7 @@
 Changing to a mass conserving slab temperature
 ===============================
 
-In the section on [slab temperature](part:user_manual:chap:basic_starter_tutorial:sec:12_subducting_plate_temp), we added the {cite:t}`McKenzie_1970` (that is the plate model) slab temperature structure. Although this is a good first order approximation of a slab temperature, the recently develop {cite:t}`Billen_Fraters_AGU_2023` temperature model has many advantages over it, with the downside that is it a bit more involved to use. In this chapter we will just switch out the plate model with mass conserving without going too much into the detail of how to actually use it in practice. If you plan to use the mass conserving temperature model, please first read through both the [Simple Subduction Model: 2D Cartesian](part:user_manual:chap:cookbooks:sec:simple_subduction_2d_cartesian)and [Simple Subduction Model: 2D Chunk](part:user_manual:chap:cookbooks:sec:simple_subduction_2d_chunk) cookbooks.
+In the section on [slab temperature](part:user_manual:chap:basic_starter_tutorial:sec:12_subducting_plate_temp), we added the {cite:t}`McKenzie_1970` (that is the plate model) slab temperature structure. Although this is a good first order approximation of a slab temperature, the recently developed {cite:t}`Billen_Fraters_AGU_2023` temperature model has many advantages over it, with the downside that is it a bit more involved to use. In this chapter we will just switch out the plate model with mass conserving without going too much into the detail of how to actually use it in practice. If you plan to use the mass conserving temperature model, please first read through both the [Simple Subduction Model: 2D Cartesian](part:user_manual:chap:cookbooks:sec:simple_subduction_2d_cartesian)and [Simple Subduction Model: 2D Chunk](part:user_manual:chap:cookbooks:sec:simple_subduction_2d_chunk) cookbooks.
 
 ## Changing the Subducting oceanic plate temperature
 One of the advantages of using the mass conserving slab temperature model is that it doesn't assume a linear temperature structure at the trench. This means we can seamlessly connect a half space cooling model or a plate model to the mass conserving slab. But for that to make sense, we need to change the subucting oceanic plate to a half space cooling model (the default for the mass conserving temperature model). In this case we will put the ridge far away. Because the half space model can affect the temperature at much deeper depths, we also need to change the max depth for the feature and models. Note that we will want to keep the max depth of the composition at 100km, so we now need to set a max depth in the lowest layer of the composition model.