Cinder cones form from volcanic pipes which spit out hot ash and cinders. For cinders to form, the cone has to spit out the gas-filled lava which solidifies quickly.

But divergent plate boundaries like the mid-Atlantic rise are usually underwater. Cinder cones can form under the sea, but water cools them quicker than air, and currents can sweep ash away. Because they're so different I'm not sure how many other scientists would call those types of cones "cinder cones." So, underwater cinder cones don't have it easy at divergent plate boundaries. Most cinder cones form from a type of lava called basalt which can form in just about any tectonic setting. We find cinder cones at a convergent plate boundaries like Chile and cones at divergent boundaries like the East African Rift. In Death Valley, part of a transform plate boundary, a fault has sliced at least one cinder cone in half.

When two continents meet, like in the Himalayas, we generally don't see as many volcanoes at the surface; I don't know of any cinder cones in continent-continent convergent plate boundaries.

But cinder cones don't even need to form near plate boundaries! Hawaii has cinder cones and scientists suggested that some volcanoes on Mars might be cinder cones.

Cinder cones may form along diverging plate boundaries, near or behind the volcanic front along converging plate boundaries and ALSO at intra plate (no plate boundary) locations called hotspots such as Hawaii. Cinder cones are not associated with any one type of petrotectonic location. In order to form a cinder cone the magma must be saturated in H₂O or CO₂ to form bubbles of gas within the liquid part of the magma.

Cinder cones can form at a variety of plate boundaries and even at intra-plate volcanoes (volcanoes away from plate boundaries).

Strato-volcanoes most often form at convergent plate boundaries (subduction zones) and smaller cinder cones frequently form on their flanks.

There is no plate boundary near Hawaii, and the volcanism is generated by a hot mantle plume. However, shield volcanoes like Mauna Kea on Hawaii, also have cinder cones on their flanks which form during the late stages of volcanism after the main shield stage.

The only plate boundary type where cinder cinder cones are not common is divergent plate boundaries (like mid-ocean ridges).

Cinder cone volcanoes form when a volcanic vent - where lava and rock debris erupt through an opening in the ground - erupts and sends lava and rocky debris into the air. The lava cools and falls down as chunks along with the rocky debris, stacking up into a cone around the volcanic vent. These chunks of debris are known as pyroclastic fragments. The formation of a cinder cone is also helped by lava flowing under the pyroclastic fragments already accumulated around the vent, spreading the fragments out into the characteristic cone shape of a cinder cone.

Cinder cone volcanoes can form in a few different tectonic settings. Many of them form at convergent plate boundaries, where oceanic crust slips underneath continental crust or other oceanic crust. We call this slip "subduction", and at these boundaries the oceanic crust gets pulled down into the mantle. As it moves into the mantle, it brings ocean water with it.When ocean water and hot mantle rock mix, the rock melts to form a magma. That magma rises up to the Earth's surface and erupts in a volcano! Because there's so much water in the magma, it causes a very "gassy" explosion, which is what forms the cinders.

Cinder cones can also form inside tectonic plates though, where there is no boundary in sight. These volcanoes form on top of something we call a "hotspot", which is where really hot rock from deep inside the earth rises up. When that hot rock gets close to the earth's surface, it melts to form a magma and erupts. An example of this is Hawaii. In Hawaii, most of the volcanoes are shield volcanoes, but there are a lot of cinder cone volcanoes that form along the flank of the shield volcanoes.

Cinder cones form along convergent plate boundaries, divergent plate boundaries, and some types of transform plate boundaries (specifically, those that involve divergence). Basically, anything that gets magma near the surface will create cinder cones, whether through spreading or through subduction.

The cinder cones in Oregon and Washington that form in-between the large stratovolcanoes that make up the Cascades are on a convergent plate boundary. The cinder cones in Nevada occur because the transform plate boundary at the San Andreas Fault is actually slightly divergent, and Nevada is being stretched because of it.

Volcanoes can form at either convergent (two plates colliding) or divergent (two plates going away from each other) plate boundaries. Different volcano types form depending on the kind of lava that erupts -- if the lava is sticky it usually forms stratovolcanos and if it is runny it forms shield volcanoes. Cinder cones can form at both convergent and divergent plate boundaries and they are pile-ups of ejected material from the volcano.