Sedimentary rocks are formed over existing basaltic rock on ocean beds.
The rock type thus formed would be sedimentary. What type of sedimentary rock formed would depend on a multitude of factors.
sediment builds up on the bottom of a lake of ocean and forms rocks or landforms
Any Type Of Limestone
The ocean floor is primarily made up of basalt rock, which is a type of igneous rock formed from solidified lava. Basalt is dark in color and forms through volcanic activity at mid-ocean ridges and hotspots.
Underwater mountian ranges/ underwater volcanoes
The color of the rock that forms oceanic crust at mid-ocean ridges is dark gray to black. The rock is primarily basalt, which is a type of igneous rock formed from the solidification of molten lava.
All rock types can be formed from any other rock type.
Organic Sedimentary rock would probably be the best answer!
Who are you
The different rock types will be from different beds or formations that have been vertically displaced. For example moving from the handing wall of a normal fault to the footwall will bring you into older beds which may be of a different rock type.
The type of rock that likely formed first to initiate the rock cycle is igneous rock.
Any type of landscaping rock of your choice will work for flower beds. www.stonedecorative.com has a wide variety of landscaping rocks.