Final answer:
In engineering drawing, holes and discontinuities are typically crosshatched to show they pass through the material, while in geology, they are marked differently to reflect geologic features, differing by context.
Step-by-step explanation:
The statement "Holes and un-continuous parts should be crosshatched through" can be discussed in relation to both engineering drawing and geology. In engineering drawing, hatch lines are used to indicate the surfaces of cuts through material, with holes and discontinuities typically being crosshatched to show that they pass through the material. This contributes to an accurate representation of the object being depicted. On the other hand, when considering geological cross-sections, the presence of holes or un-continuous parts might not be crosshatched, but rather, they should be marked to reflect true geological features such as voids or discontinuities within the earth, which can be critical for interpreting the geologic history of an area. Depending on the context, the approach to depicting these features can vary significantly.