Geologic logs are prepared from examination of drill cuttings (samples). Well drillers are usually required to submit drill cuttings to WGNHS for wells which are: (1) high capacity (>70 gpm), such as irrigation or industrial wells, OR (2) public water supply wells, such as those for municipalities, schools, parks, or waysides.
Unfortunately, there are many wells for which WGNHS should have samples, but doesn’t. Reasons include: (1) samples not collected by well drillers, (2) samples collected but not submitted to the Survey, (3) samples sufficiently damaged after collection so as to render them useless (4) samples collected but not labelled, therefore also useless, (5) very difficult or unusual drilling conditions, which make sample collection difficult and/or samples collected meaningless.
When drill cuttings are received from the well driller, WGNHS geologists prepare geologic logs. These geologic logs contain a detailed description of each sample. Because a sample is usually taken every 5 feet, these logs usually give much more detailed geologic information than the WCRs. The geologic logs are only available in paper form.
Page-size index maps are available on request.
- Logs: $1 each + labor ($5 minimum per order) + postage/handling ($5 minimum).
- Fax: adds $1/page ($5 minimum)
- FedEx (on your account): adds $5 to total
Every geologic log produced since 1936 should (but sometimes doesn’t) have a corresponding WCR. The two files are cross-referenced, but it would usually cost much more in hourly charges to have WGNHS personnel omit the few unnecessary WCRs than it would to pay for the copies. In rare cases the WCR was received after the geologic log had been published, and contains well construction data that is probably missing on the geologic log. Many geologic logs exist for wells for which no WCR was ever received.