The measurements at the Pytlikova cave site were done to look for the extension of the smaller side cave, located just a few tens of metres away of the main cave. The measurements in the surroundings could verify if there are some similar caverns or voids nearby. A rather long profile through a rocky slope over the entrance of the cave and back is depicted on the aerial image below.
Radargram shows a reflection from Pytlikova cave at position 50 m at around 21 m depth (recorded on profile direction forward) and at position 250 m at 17 m depth (profile backwards). A strong reflection was registered at position 370 m, but it is right in the place of profile turning, so its shape is prolonged – we have probably touched only a side of another cavern. A sharp, but not so strong reflection appears at position 300 m at depth of 23 m, accompanied with a series of reverbed reflections fading out to the lower part of the radargram, probably caused by wave resonance. This void is most interesting, according to us, as it probably has distinct ceiling and almost vertical wall (represented by inclined linear reflections). Unfortunately, the radar wave resonance, recorded as repetitious reflections, masks a part of the underground information.
This void was also found on the next, parallel profile (see below) at position 24 m. Another strong reflection arrives at position 50 m (coincides with turning spot of the previous profile) and represents even larger cavern.
Another set of parallel profiles in the south-west direction has, most probably, revealed the continuation of this cavern in almost the same direction, despite shifted a bit.
Another step would be horizontal surveying on the back wall of the cave, aiming to find the shortest path to another void.
The void in 40 m depth is broadening with the distance, but it is approx. 15 – 20 m lower than the entrance section. More profiles in different directions would help to map this feature but unfortunately, we didn’t have enough time as we rushed to do another measurement elsewhere.
I was really glad I could help the speleological group Topas to clear up the direction of further research under the ground. Many thanks to Mr. I. Audy for the pictures from locations in the Pytlikova cave surveyed from the surface.