The Mid-Pacific Mountains lie west of Hawaii and northeast of the Marshall Islands, but at the time of their formation were located in the Southern Hemisphere.

It drowned about 99 ± 2 million years ago for unknown reasons; possibly a phase of renewed emergence damaged the reefs, or it was located in unfavourable waters.

[8] These drill cores were part of a larger project to investigate and clarify the history of the flat-topped submarine mountains in the Pacific Ocean.

[15] Hawaii lies due east and the Marshall Islands southwest;[16] Resolution Guyot is 716 kilometres northwest.

[17] The guyot[4] (also known as tablemount[18]) has an outline resembling a trapezoid[13] and consists of two connected volcanic ridges facing north-northwest to east-northeast.

[21] The structure appears to consist of lagoonal sediments surrounded by a reef,[24] and the shallowest point of Allison Guyot lies at less than 1,500 metres (4,900 ft) depth below sea level.

[26] The seamount bears traces of slumping,[27] which on the southeastern side of Allison Guyot has removed part of the platform perimeter.

Underneath Allison Guyot, the seafloor is about 130–119 million years old,[15] and a 128-million year-old magnetic lineation is located nearby.

[32] These are submarine mountains which are characterised by a flat top and usually the presence of carbonate platforms that rose above the sea surface during the middle Cretaceous period.

[39] Sometimes volcanic activity continued after the formation of the atoll or atoll-like structure, and during episodes where the platforms rose above sea level erosional features such as channels and blue holes[b] developed.

[11] One drill core on Allison Guyot has found a 136-metre-thick layer of pelagic sediments, under which are 735-metre-thick limestones that formed in lagoons[9] and might continue down for almost 600 metres.

[17] The limestone consists mostly of calcite with little dolomite[44] and occurs in the form of bafflestone,[45] grainstone, packstone, peloid, rudstone and wackestone;[46][47] ooliths have also been found.

[56][57] The basalts are typical of intraplate volcanism[58] and their geochemistry shows evidence that fractional crystallisation and mixing between different magmas were involved in their genesis.

[49] They consist of berthierine, chlorite, feldspar, hydromica, illite, kaolinite, mica, quartz, serpentine, smectite and possible zeolite.

[47] The lower limestones contain substantial amounts of organic material that originated from terrestrial settings,[70] and remnants of animal burrows[71] and plant roots have been found[51] in many layers of the platform.

[55] Paleomagnetic data taken from limestones show that Allison Guyot developed in the Southern Hemisphere, at a latitude of about 11.2° ± 2.0° south.

The interior was not protected from the sea[77] and the sector of the platform that was investigated by drill cores apparently became increasingly accessible to it over time.

[84] At some point, karst environments existed on Allison Guyot and are probably the reason for the irregular surface of the summit platform[85] and the presence of sinkholes; there are clear indications of about 200 metres of emergence.

They indicate that such species lived within the lagoon of Allison Guyot and may give clues about the history of Pacific animals and their dispersal.

[93] On both Allison and Resolution Guyots, the drowning was preceded by an episode where the platform rose above the sea;[94] possibly it was this emergence and the following submergence which terminated carbonate deposition and prevented it from beginning again.

[95] Such emergence and drowning has been recorded at carbonate platforms of that age around the world and may be the consequence of tectonic events across the Pacific Ocean,[86] culminating in the uplift of a part thereof.

[50] As plate tectonics moved Allison Guyot northward, its surrounding water masses changed, as did the properties of the pelagic cap.