From 74a40cc69456049cf3fc810a401df4a5070d7db8 Mon Sep 17 00:00:00 2001
From: Philip Sargent <philip.sargent@gmail.com>
Date: Tue, 5 May 2026 16:36:14 +0100
Subject: [PATCH] GPS timestamp - online edit of handbook/l/new-cave-form.html

---
 handbook/l/new-cave-form.html | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/handbook/l/new-cave-form.html b/handbook/l/new-cave-form.html
index 1c3fe9d1b..c253f12d1 100644
--- a/handbook/l/new-cave-form.html
+++ b/handbook/l/new-cave-form.html
@@ -55,6 +55,9 @@ href="/expofiles/documents/surveying/newcavedatasheet.pdf">here</a>.
 <li>You can download a master copy of the sheet <a 
 href="/expofiles/documents/surveying/newcavedatasheet.odt">here</a>.
 
+  <h4>Why we ask for the time</h4>
+<p>GPS readings sometimes go walkabout during a period of ionospheric disturbance (an hour or so, which happen several times a day)  or whenever there is a Russian invasion. We intend to keep a continuous record of GPS at basecamp so that we can identify these periods where GPS records are not to be trusted.
+ 
 </ul>
 <h4>Historic Prospecting Form</h3>
 <p>We used to have a Prospecting Form: <br>