What clues reveal connections between the past and the present in holes story?

In "Holes," the connection between the past and the present is revealed through the interwoven stories of Camp Green Lake's history and the current circumstances of Stanley Yelnats. The repetition of the Yelnats family curse and how it ties back to Stanley's great-great-grandfather's promise to Madame Zeroni helps illustrate this connection. Additionally, the discovery of Kissin' Kate Barlow's backstory through flashbacks further highlights the impact of past events on the characters' present experiences.