Oceanic trench the level of the surrounding oceanic floor. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km/yr. There are approximately of convergent plate margins, mostly around the Pacific Ocean—the reason for the reference “Pacific-type” margin—but they are also in the eastern Indian Ocean, with relatively short convergent margin segments in the Atlantic Ocean and in the Mediterranean Sea. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km or about 0.5%
Capture of Regina Trench The left-hand battalion was stopped in front of the trench with many casualties and the brigade withdrew at nightfall. A few troops of the right-flank battalion of the 9th Canadian Brigade, 3rd Canadian Division got into Regina Trench through some German sally ports but was overwhelmed. The battalion on the left flank, reached Regina Trench at the junction with Courcelette Trench but was then forced back. Part of the 7th Canadian Brigade reached Regina Trench, began to bomb westwards and also worked up the West Miraumont road but was eventually forced back by German counter-attacks. The left hand battalion was