The foundation has worn away so much that you can see daylight! The mudsill should not have a gap like this
The repair for Spalling is to pour new concrete to rebuild the wall that has deteriorated and fix any drainage problems.
Houses that were built before the 1940’s sometimes were built on uncompacted fill. This is not good, because soil tends to expand and contract at different times of the year when moisture levels changes, which can cause damage. The type of soil that is underneath the foundation also plays a key role. Clay soils tend to expand and contract the most.