Cave systems do exist in the Leningrad Region. The most famous and system of caves near St. Petersburg - Sablinskie (on the Sablinka River).
Let's say right away that the vast majority of caves existing in the Leningrad Region are of artificial origin - they are mine workings, that is, abandoned places where sand or stone was previously mined. In the case of Sablino - sand. These caves are of relatively recent origin.
In the 19th century St. Petersburg experienced a period of rapid growth, the heyday of the construction boom. The houses required glass, and for its production - quartz sand. Soon the need to produce glass bulbs was added to this need. In the late 19th and early 20th centuries, electricity began to spread widely in the city. And it was also necessary to produce dishes, chemical glass.
It should be noted that glass factories gravitated towards regions where deposits of quartz sand were found. In various statistical reference books, we see the following entries: “Away from the Babino station, 20 versts to the west, near the village of Chervina (residents about 250 hours), there is a Nechaev-Maltsev glass factory under the Tigoda glass factory by the Tigoda river. producing, with 60 workers, green and bemsky glass for the amount of over 50 thousand rubles."
“Chudovsky glass, crystal and lamp factory of IE Kuznetsov, founded in 1878, at a distance of 1½ ver. from the station (on the highway). The plant with 926 workers annually produces products worth about 357 thousand rubles."
Luga Uyezd: “Factory industry: the first place is occupied by glass factories (8), the number of which is increasing every year due to the abundance of white sand, especially along the banks of the river. Oredezhi. A glass factory owned by the Kurzhenkov brothers has been set up near the post; existed since 1837. The main products of the plant are glass for electric, gas, lamp lighting, crystal dishes and stationery. The factory employs about 600 workers. The plant's annual production amounts to about 500 thousand rubles."
Sand extraction was carried out both by the open method and in shallow workings. Often, safety precautions were not followed, supports were not installed. All known cave systems were located near glass factories (with the exception of the Telesi system, which is discussed below).
There are many old caves or small grottoes where sand was mined in the Oredezh River basin. Several workings were located along the Volkhov bank in Staraya Ladoga. Their history is very revealing. Archaeologists of the 19th century mention peasants excavating the banks and interfering with the work on the study of monuments. One of the workings was directly under the church of St. John the Baptist of the 16th century. And already in the XX century, the closed temple began to collapse due to the voids under it.
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During the reconstruction at the end of the 20th century, the caves had to be filled with concrete. Now the entrance to the cave under the temple is closed. But the system of caves in a kilometer from the first one, behind the Sopki tract, has been perfectly preserved. Legends also attribute tens of kilometers to it. But the system remains open to the public.
In general, the popularity of caves in the vicinity of the city coincided with the late 60s - early 70s and continued to grow throughout the end of the 20th century. Dozens of formal and informal associations of speleologists held training sessions and meetings in Sablino and other caves. It was from this environment that the largest number of legends about dungeons, caves, "white arrows" and "black cavers" came out.
The fate of the Sablinskie caves was successful - they were recognized as a natural monument, became a specially protected natural area. Now there is an active educational and recreational activity. We can say that this is an example of how to handle natural and historical heritage.
Less fortunate is the cave system in the Telezi area beyond Krasnoe Selo. These caves are located in the zone of occurrence of a thick layer of limestone. The Pudost slab was and remains a popular building material in St. Petersburg and its environs. Moreover, the limestones mined on the Izhora plateau (beyond Krasnoe Selo) were the basis for creating a construction mixture at a time when cement had not yet been invented. Its main component was quicklime, which was made by burning from tuff and limestone quarried southwest of the city. So it is safe to say that limestone was the most widely used building material. In most cases, it was mined in an open way. But in the area of the village of Telezi - in underground workings - the stone apparently lay under a larger layer of sedimentary rocks than in other places.
The workers left the caves, and cavers appeared there in the second half of the 20th century. The system of caves was formed very dangerous, threatening with constant collapses, which was repeatedly mentioned at forums and conferences of experts. She did not receive a security and, moreover, a recreational status. The people who examined it were there at their own peril and risk. Now most of the caves of the Telesi system have come under construction in connection with the construction of a transport bypass in Krasnoe Selo.
There are also reports of the presence of caves in the area of the Lava River canyon, east of St. Petersburg. The mentioned canyon is undoubtedly a natural monument. The lava cut a twenty-meter gorge through the limestone. In the spring, springs flow from the walls of the ravine. The author was able to examine the river canyon in great detail during the years of archaeological excavations at the so-called "Lavuysky Ostrozhka" - a fortified point on the border of Russia and Sweden, built in the 17th century. The locals showed "caves", but they all looked more like gullies formed as a result of soil erosion. It was not possible to find a developed system of halls there.
There are not so many caves near our city. Having ceased to be industrial facilities, they have taken on a life of their own - groundwater creates lakes in them. Bats hibernate on the walls. The beautiful layered sands create beautiful natural scenery. Protection and reasonable use for the purposes of education and recreation, sports training - this is the future for these monuments.