Cesu district, rural municipality Straupe.Drive through Straupe and then follow signs on the left side of the road right after cafe "Skesteri" (if you are on way from Riga).
Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite.
Karst springs occur where the groundwater flow has concentrated to dissolve a conduit in soluble rock. Over a period of time underground fractures enlarge due to the bedrock dissolving that creates an underground drainage system. The process of erosion starts slowly but as the fractures in the rock increase in size, it allows more water to enter and accelerate the karst formation.
The karst effect have quite dramatic impact on people life due to as the bedrock continues to dissolve, it may not be able to support the weight of the ground above it. When that happens, the roof of the cave /cavern collapses which results to a sinkhole. Farming is often difficult because the land may be suitable to farm but rainfall doesn't provide enough water for the crops since it disappears into the cracks that have formed in the area. This leaves the ground parched between rains and limits the ability of the crops to grow.
GEOLOGY OH THIS SITE
The one of the most representative geosite of Northern Europe,
Braslas Ezerala (a.k.a. Vejinu Ezerala as well Urtanu cave) is underground lake formed by sandstones suffosion.
Vejinu Ezerala (Braslas Ezerala) is 48 m length cave system with underground spring and two underground lakes - only known underground lake in Baltic states.
Width 2,3 - 6 m, height 0,9 - 1,7 m, floor area 160 m2. Cave is right beside Brasla river and is flooded when water level in river is high. Cave other end is closed by sinkhole that is also closing underground spring. As result there are two underground lakes the small lake area is - 15 m2, length 6 m, approx. 5 m depth. Above big underground gap is just 6m chunky sandstone and quarternary layer.
"Holes of the hell" is the biggest suffosion sinkholes in Latvia. In several hectares area there are by suffosion shaped eight deep and wide sinkholes. In year 1984 after land amelioration 3 sinkholes were filled in and flattened. The biggest sinkhole size is 30 x 20 m, depth 7 meters. These sinkholes are indicating about several hundred meters long underground tunnels or even tunnels systems. Sinkholes claim many homes and cars each year without warning. Locals are telling stories about some very deep cave which leads from riverside to the road and even behind it. Dozen years ago there were also very beautiful sandstone bridge - huge natural sandstone arch that was eroded and collapse into the river.
Probably existing Ezerala is just part of huge underground labyrinth system.
Task: 1. Tell me is there are any stalagmites or stalactites at the cave entrance?
2. To measure the distance from ground level (footpath/top platform) to the water surface (lowest step). Due to level of water surface depends on floods you should count all stairs from top platform till the very last stair step down to the water surface. Then you should multiply it by 20 cm (one stair average step) and send me the total depth from the top ground surface to water surface below.
3. Taking photo of yourself with GPS unit in your hand in front of the cave entrance (upper or lower its up to you) and posting it into your log is an optional but not mandatory feature.
4. Send your answers to the developer, and wait for the permission to log your visit.
My congratulations to Vilnis & Juris1C with Ezeralas FTF - you were fast as lightning
|I am a proud