1. n. [Formation Evaluation]

The top of the interval recorded on the log, or the shallowest point at which the log readings are valid. If the top of the log is at the casing shoe, the last valid reading of many logs will be a short distance below. However, it is common to give the depth of the casing shoe as the top log interval.

Antonyms: bottom log interval

See: casing shoe,  last reading