Improving figures based on Becky's comments.

doc/sphinx/user_manual/basic_starter_tutorial/10_adding_basic_subducting_plate.md

@@ -12,7 +12,7 @@ There are five properties these line features objects require:
 4. `dip point`: This is often most confusing to new users, but the concept is really simple. If the slab or fault makes an angle, we need to decide what side of the line (trench for a slab) the slab or fault is dipping. There are many ways of doing this, but in GWB it is done through simply defining a point on one side of the line. The slab or fault will then dip in that direction. It is often good to choose a point far away from the trench, especially if the trench makes a lot of curves.
 5. `segments`: Defines the downwards part of the subducting plate (i.e. the slab) or fault. Each segment requires at least a `length` as a number, a `thickness`, which is an array of one or two numbers and an `angle`, which is also an array of one or two numbers. We will first show an example to get our first slab in the model before explaining further. It will hopefully be easier to understand when you see it in action in this and the next few sections.
 
-For the example in this section, we will make a trench at the interface of two area features, where the slab is dipping with a constant angle of 60 degrees in the direction of the overriding plate. We make this slab (segment) 300 km long and give it a constant thickness of 100 km. So we set a dip point at a location on the side of the overriding plate with respect to the trench. In this case the origin (0,0) will work fine. 
+For the example in this section, we will make a trench at the interface of two area features, where the slab is dipping with a constant angle of 60 degrees in the direction of the overriding plate. We make this slab (segment) 300 km long and give it a constant thickness of 100 km. So we set a dip point at a location on the side of the overriding plate with respect to the trench. In this case the origin (0,0) will work fine and the location is shown as the turquoise sphere in the figure below. 
 
 ```{note}
 The result will not change based on the exact location of the dip point, as long as it is on one side of all the lines formed by connecting the line features coordinate points.
@@ -76,5 +76,5 @@ The explanation can be significantly improved by adding conceptual figures
 :alt: Basic Starter Tutorial section 10. 
 :align: center
 
-Basic Starter Tutorial section 10. The top part of the figure shows where the composition as been assigned as an object. Currently it shows composition 0 as green, composition 1 as yellow, composition 2 as purple and composition 3 as blue. Composition 4 is not shown to be able to see the slab. The front half of the overriding plate (composition 1) has also been removed to be able to better view the slab. The bottom part shows the temperature as seen slightly from below where only temperatures between 300K and 1600K are shown. 
+Basic Starter Tutorial section 10. The top part of the figure shows where the composition as been assigned as an object. Currently it shows composition 0 as green, composition 1 as yellow, composition 2 as purple and composition 3 as blue. Composition 4 is not shown to be able to see the slab. The front half of the overriding plate (composition 1) has also been removed to be able to better view the slab. The turquoise sphere is the location of the dip point. The bottom part shows the temperature as seen slightly from below where only temperatures between 300K and 1600K are shown. 
 ```

doc/sphinx/user_manual/basic_starter_tutorial/16_2D_models.md

@@ -64,6 +64,14 @@ You need to change the gridfile to a 2D grid to be able to see the difference.
 ```
 
 
+```{figure} ../../../../doc/sphinx/_static/images/user_manual/basic_starter_tutorial/BST_16_3D_cross_section.png
+:name: BST_16_3D_cross_section
+:alt: Basic Starter Tutorial section 16 highres result. 
+:align: center
+
+The location of the 2D cross-section in the 3D model. The turquoise arrow show at the dot `[0,200e3]` and at the arrow head `[100e3,200e3]`, where `[0,200e3]` is the origin of the 2D plane. The semi-transparant turquoise plane show the full cross section location.
+```
+
 ```{figure} ../../../../doc/sphinx/_static/images/user_manual/basic_starter_tutorial/BST_16.png
 :name: BST_16_highres
 :alt: Basic Starter Tutorial section 16 highres result.