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discovered answers to my own question which has led to a follow up question
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What is the meaning of these two inverted triangle water table symbols in a borehole record?

Consider the borehole record below (in particular the Water Depth column).

There is a white inverted triangle at a depth of 3.20 m. What is the meaning of this symbol?

The white inverted triangle indicates the depth at which water was struck.

There is a black inverted triangle at a depth of 2.50 m. What is the meaning of this symbol?

The black inverted triangle indicates the depth to which the water rose after 20 minutes.

My new question is why does the water rise above where it was originally struck? What is this implication of this? Is the location of the black inverted triangle the true location of the water table within the soil? Why was water struck lower than this?

borehole record

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