The sinkhole is very long, and after a few hundred meters of progress in the sinkhole, the explorer can finally enter a relatively spacious place, which is a small lava crevice, the ground is slightly wet, and the surface layer is very shallow water flowing slowly. The pen "Fun" Pavilion www.biquge.info with this amount of water, it is estimated that it will take half an hour to fill a mineral water bottle.

This is obviously groundwater seepage, and if it rains outside, it is estimated that the water flow here will become larger, and from the size of this crevice, it can be estimated that the formation time here is not too long, and it is estimated that it will look like a few hundred years.

In the karst terrain area, there is a hundred rivers on the ground to the sea, and there is another set of rivers to the sea in the ground. As the cap of a mountain peak, it is estimated that it is the origin of an underground river, or the source of a tributary.

Following the guidance of the survey structure, the explorer continued to go deep underground in the direction of the current, and while the explorer explored, the Sky Survey Eagle was hovering overhead.

Now that the Eagle had lowered its flight altitude, it was hovering over the hill, and the detection radar was aimed at the direction of the explorer, constantly switching between bands and scanning over and over again. Under this high-precision detection, the geological structure around the explorer is unusually clear.

"Try an ultrasound scan!"

Watching the explorers swim in the lava cracks underground, Meng Yang decided to test the relevant organs, see the effect first, and don't find that you can sit on wax if you don't use it when you need to use it.

With Meng Yang's order, the explorer's head began to change, a bulge appeared on the position of the nose, the ears began to expand and become larger, and a bat ear began to grow on the head of the original lizard.

Chirping!

A sound wave, which is completely inaudible to the human ear, is emitted in a fan-shape, and then these sound waves continue to bounce, refract, and reflect on the surrounding rocks, and the echoes are collected by the ear, and after various processing, the surrounding terrain is slowly outlined.

Comparing infrared visual images and detection results, the ultrasonic positioning accuracy is still good, but unfortunately its working range is a bit short, it can only scan the terrain within 50 meters, and there will be blur and errors further away, which is estimated to be related to the terrain environment and distance loss.

"Test the structure probe."

Chirping!

This time, the fan-shaped sound wave was not emitted forward, but directly towards the rock formation under the explorer's feet, and the ultrasonic wave hit the rock, most of which was reflected back, and a small part went directly into the interior of the rock and continued to propagate downward.

Sound waves propagate within the rocks, and as they propagate, various refractions occur constantly, and a large number of echoes are fed back to the surface. These echoes are collected by the ear, and the internal structure and density changes of the rock are clearly outlined.

The detection distance of the rock formation is only more than two meters, and more than five meters is completely impossible to collect valuable echoes.

"Turn on the infrasonic detector."

Ultrasonic directivity is very good, but infrasound is the opposite, it is difficult to use as an active detection wave, but it is just as valuable.

A large number of infrasound waves will be generated in the environment, most of which are relatively weak, but large-scale geological and climatic activities will produce powerful infrasound waves, which have practical detection significance and can be used to warn of geological disasters and climate change.

Close-range infrasound detection can be used as a means of biological detection, and it is also of great value in disaster search and rescue.

The explorer's eardrum shifted slightly, and the infrasonic reception mode was activated.

The surrounding noisy infrasound waves were immediately revealed, including the infrasound caused by the flow of air, the sound of the mountain wind skimming over the trees, the tremor caused by the uneven heat and cold contraction of the mountain, the sound of the water rushing over the rock wall, and even the sound of the internal organs of living beings......

These sounds are like background noise, after countless refractions and diffractions of the mountain, the source direction has been completely blurred, and the only thing that can be done is to tell who made these sounds.

Although most infrasound waves cannot be identified in the direction of their source, some sound sources that are relatively close together can still be distinguished. The sound of one of the bodies of water flowing, more than forty meters below.

"Compare the probes."

Calling up the detection map, more than 40 meters below the explorer is a dark river, the amount of water in the dark river is not large, about two or three cubic meters per second, that is, the level of a small stream.

"Keep going."

The Dark River has nothing to do with the object of this exploration, it crosses under the explorer, and after a few kilometers it re-emerges from the surface and becomes a clear spring.

The explorers have gone deep into the ground for nearly 100 meters, and the temperature in the dissolution crevice is constant at about five degrees above zero, the humidity is not high, and the carbon dioxide content is much smaller than that of the surface.

The carbon dioxide in the air is constantly absorbed by the surrounding water molecules, which again combine with the surrounding limestone and become soluble minerals. Once the water passes through, it carries these solutes with them and slowly erodes the karst formations that are unique to the limestone formations.

The lava fissure soon came to an end, and explorers appeared on the side wall of a cave full of stalactites of all sizes, and the roof of the cave was dripping with droplets, converging into an underground river at the bottom of the cave. The cave is not large, only a dozen meters wide, and the shallow part of the underground river is only half a meter deep.

"Switch to dive mode."

The explorer began to deform as he lay on the cave wall, first growing a pair of gills, a lizard's tail transformed into a fish's tail, and twenty pairs of small short legs changed from eagle talons to duck paws.

Soon the conversion was complete, and the explorers climbed down the cave wall and dived into the water, and the ultrasonic and infrasonic sondes had just turned on to pick up some strange signals. The shape of the sound source is quickly outlined by the outline of ultrasound, which is a fish about twenty centimeters long.

"Get closer and look closer, turn on the searchlights."

A searchlight rises above the explorer's head, which is made up of enhanced glowworm cells that combine into a small flashlight shape that converges into a straight beam.

A beam of light appeared in this dark cave, probably the first light to appear in this cave in hundreds of thousands of years.

The light illuminated the mirror image of the bottom of the water, and a strange fish with a nearly transparent body appeared in the field of vision, this fish looked like an enlarged and elongated tadpole, without any color on its body, its whole body was translucent, and its internal organs were clearly visible.

The strange fish did not react to the sudden appearance of light, and its head had no eyes, only two black spots that were not obvious, which were obviously degraded eyes.

Its mouth resembles a tadpole's mouth, resembling two pieces of skin that open and close, with neither teeth nor a normal mouth contour, like a small opening in its head.

It seems that this cave is inhabited by living creatures.

"Turn on the biodetector."

It's a bioelectric probe officer, and when it starts working, sparkles of life emerge around the explorer.