What is the default behavior of the Drupal 7 cache?
To find out all events when page and block cache is cleared - you can search through all modules for using of cache_clear_all() function.

Here is brief list of such events in Drupal core.


Any content is created or updated (nodes, taxonomy terms, comments, etc)
Content permissions are updated. 
Block is created or updated.
Vocabulary created, edited or deleted.
Any settings form in admin back-end is submitted (those forms that use system_settings_form()).
User account is created, updated or canceled.


As you see page and block cache is not cleared automatically when any content is deleted.