http://vro.dpi.vic.gov.au/dpi/vro/coranregn.nsf/pages/corangamite_eruption_points_bullen_merri Lake Bullen Merri lies in a deep maar crater of a clover-leaf outline measuring 3.2 km x 2.8 km. It is surrounded by a tuff ring and a lava flow is exposed discontinuously in the crater wall. Limestone sediments of Tertiary age are also exposed. Rare metapyroxenite xenoliths rich in A1-spinel and garnet are present. The shape of the crater may be due to the coalescing of two or possibly three maar craters. The crater has a steep cone-shaped floor with the base at about 80 m above sea level. The higher points around the rim average 250 m. Present maximum water depth is 67 m with a mean depth of 40 m. http://austhrutime.com/lake_bullen_merri.htm This is a cloverleaf-shaped twinned crater, the other twin being Lake Gnotuk. It is believed it may have originally been 2 or 3 maars that coalesced as the their perimeters were enlarged by subsequent eruptions. Its surrounding wall is of tuff, and there is a lava flow exposed discontinuously in the crater wall. There is also an exposure of Tertiary limestone sediments in the wall. Its sediments span the last 16,000 years. There is a steep cone-shaped floor, that is 80 m above the sea level at the base. The rim is 130 m above sea level. It is separated from Lake Gnotuk by a saddle, which is the overflow point, any excess water flowing into Lake Gnotuk. The latest know overflow was in 1841. Around the lake there are a number of well-defined terraces, demonstrating high water levels in the past. These and Lake Keilambete all erupted through the Port Campbell Limestone. In the strata around the lakes the groundwater derives from 2 sources. The lower source is a low-yielding confined aquifer in the Port Campbell Limestone. There is also an unconfined aquifer at the base of the tuff, which forms a perched watertable surrounding the crater. Both aquifers merge near the lake, supplying the springs around the edge of the water. Website: http://www.aboveandbeyond.nu Tour Dates: http://www.abwall.com Facebook: http://www.facebook.com/aboveandbeyond Youtube: http://www.youtube.com/aboveandbeyond Twitter: http://www.twitter.com/aboveandbeyond Google+: http://bit.ly/ab-google TATW Podcast: http://bitly.com/tatwpodcast iTunes: http://www.itunes.com/aboveandbeyond Anjunastore: http://www.anjunastore.com/ Spotify: http://spoti.fi/above-and-beyond Mixcloud: http://www.mixcloud.com/aboveandbeyond Soundcloud: http://www.soundcloud.com/aboveandbeyond Follow GoJoMedia on Facebook https://www.facebook.com/GoJoMedia