LOCATION
Cesu district, rural municipality Straupe.Drive trough Starupe and
then follow signs on the left side of the road right after cafe
"Skesteri" (if you are on way from Riga).
BACKGROUND GEOLOGY
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. Then you should multiply it
by 20 cm (one stair average step) and send me the total depth from
the surface.
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 congratulaion to Vilnis & Juris1C with Ezeralas
FTF - you were fast as lightning 
| I am a proud |
 |
