Although Twylo is similar to Earth in its land-water composition, its land masses are clumped together in only three main continents.The northernmost continent in Elfhook and this continent contains most of Twylo's 2% ice. Elton is the southernmost continent and also contains some ice. The main continent on Twylo is Equat and this continent comprises 80% of Twylo's land. More than half of Twylo is covered by Vernus, a huge ocean, and no land masses can be seen in the largest part of this ocean.
This map shows Twylo with its three continents and two oceans.
Equat is quite diverse in its geologic formations. A large volcano named Flank is still active just above Twylo's equator. Two major mountain ranges contain altitudes as high as 6,000 feet. Tropical forest areas are seen along the coastal areas and these areas are just 500 feet above sea level. Low lying-plains are seen in the interior of Equat and these range between 1000-1100 feet above sea level.
This map shows a view from the south pole of tropical forest areas (in dark green) with altitudes of 1000 feet or less. The gold areas show the plains areas which average 1,000-2,000 feet above sea level. The brown areas are the mountain regions, ranging up to 5,000-6,000 feet in height.
One of the more interesting geological formations of Twylo is a large impact crater named Zam. Rocks in this area underwent shock metamorphism as evidenced by their chemical makeup. Traces of siderphile elements including iridium, osmium, and palladium have been found in Zam and give clues to the meteor which caused the crater. Zam is abundant in silica-rich glasses known as tektites. These tektites range in color from black or dark brown to grey or green and most are spherical in shape. The tektites were formed as the meteor entered Twylo's atmosphere and particles completely melted. The melted particles were dispersed as droplets and strewn about the area surrounding Zam.
The world ocean covers 77% of Twylo's surface, or about 361 million sq km. Its average depth is 5000 m. The deepest point is about 11 Km. The major subdivisions of the world ocean are the VERNUS OCEAN which almost surrounds two thirds of the planet, and the FRATER OCEAN, the innermost ocean, bounded by the continental masses of EQUAT, ELFOOK and ELTON. From the shorelines of the continents a submerged part of the continental mass, called the continental shelf, extends seaward an average distance of 70 Km. In the central parts of the VERNUS and FRATER oceans are the MIDOCEAN RIDGES, which are extensive mountain chains with inner troughs that are heavily intersected by cracks, called fracture zones. Ridges formed when lava erupted out of the cracks, which opened as the seafloor was being stretched.
The ridge system seems to merge into the continents in several areas, such as South Equat and North Elfook. Such areas are regions of great geologic activity, characterized by volcanoes, or earthquakes and faults.
The midocean ridges play a key role in plate tectonics, for it is from the inner troughs of these ridges that molten rock upwells from Twylo's rigid crustal plates. The plates are moving apart and being forced against adjacent plates. From the Mid-Vernus Ridge, the continents, which rest on plates and which once were joined, have moved away from one another. In the Frater Ocean, plates are also moving apart, but the bordering plates are overlapping them and forcing them under the edges. At these places, along almost the entire rim of Equat, deep trenches are formed as crust is subducted and returned to the mantle. The Vernus trenches commonly reach depths of more than 6 Km. Trench areas, or subduction zones, are characterized by volcanic and seismic activities, indicative of the motions and stresses of Twylo's crustal plates.
The ocean floor is covered by an average of .5 Km of sediment, but the thickness varies up to about 7 km in the HEFESTUS BASIN in the south Vernus Ocean. Some regions, particularly the central parts of the midocean ridges where new crust is formed, have little, if any, sediment on them.
The sediments are found to consist of rock particles and organic remains; the compositions depend on depth, distance from continents, and local variants such as submarine volcanoes or high biological productivity. Clay minerals, which are formed by weathering of continental rocks and carried out to sea by rivers and wind, are usually abundant in the deep sea. Thick deposits of such detrital material are often found near mouths of rivers and on continental shelves; fine particles of clay are spread through the ocean and accumulate slowly on the deep-ocean floor. These sediments are stirred up and periodically redistributed by fierce current-generated disturbances that are like storms in the deep part of the ocean.
Also, accumulated as sediment on the bottom of the ocean are the calcium carbonate shells of small organisms such as the siliceous shells of marine protozoans.