Editing Ocean Drilling Program (section)

== Scientific Accomplishments ==
The ODP and the other ocean drilling programs produced evidence that significantly improved understanding of oceanic process, spanning geochemistry, biology, and other associated Earth science fields.

=== Earth Processes ===
[[File:(Manuscript_painting_of_Heezen-Tharp_World_ocean_floor_map_by_Berann)_2.jpg|thumb|Seafloor Topography Map]]
Evidence from the ODP has led to better understanding of overall Earth processes. Most importantly, previous theories of [[seafloor spreading]] were confirmed.<ref name=":0" /> Additionally, scientists gained insights into the oceanic [[lithosphere]], including its structure and composition as well as its formation.<ref name=":0" /> The ODP provided evidence that lithospheric composition varies depending on proximity to nearby seafloor spreading.<ref name=":0" /> Additionally, geological evidence from these expeditions provided a more detailed understanding of Earth's climate and ocean history, advancing the fields of [[paleoceanography]] and [[paleoclimatology]].<ref name=":0" />

==== Geomagnetism ====
[[Earth's magnetic field]] is generated by convection in the fluid outer core. In the past, this magnetic field has experienced reversals, in which the [[North Pole|North]] and [[South Pole|South Poles]] flip. Evidence of these reversals is contained in sediments, and samples from the ODP led to more precise [[Geologic time scale|geologic time scales]].<ref name=":0" /><ref name=":1" />

==== Gas Hydrates ====
In certain subsurface environments with high pressure and low temperature, some gases, such as methane and carbon dioxide, can bond with water, forming ice-like substances.<ref name=":0" /> The ODP's Leg 164 at [[Blake Plateau|Blake Ridge]] was the first site to focus on [[Clathrate hydrate|gas hydrates]].<ref name=":0" /> Recovery of gas hydrate sediments was difficult, due to the specific conditions in which they form, which led to the loss of material during the recovery process.<ref name=":0" /> New technology was used to obtain [[in situ]] data without having to extract the gas hydrates.<ref name=":0" /> Prior to the ODP, scientists had vague estimates of amounts and locations of gas hydrate formations. Data from the program increased certainty and provided more concrete evidence of the distribution of gas hydrates.<ref name=":0" />

==== Hydrothermal Vents ====
As cold seawater enters the ocean crust at a [[hydrothermal vent]], it is heated by subsurface [[magma]] and erupts from the vent.<ref name=":0" /> This process is driven by water-rock reactions beneath the ocean floor, so evidence from the ODP has led to better understanding of these reactions.<ref name=":0" /> This is essential to understanding overall [[marine chemistry]] and interactions between the ocean and Earth's crust.<ref name=":0" />

=== Biological Processes ===
Prior to the ODP, there was little definitive evidence confirming whether or not bacterial populations exist in subseafloor sediments.<ref name=":4">{{Cite journal |last1=Parkes |first1=R. John |last2=Cragg |first2=Barry A. |last3=Wellsbury |first3=Peter |date=2000-03-13 |title=Recent studies on bacterial populations and processes in subseafloor sediments: A review |url=http://link.springer.com/10.1007/PL00010971 |journal=Hydrogeology Journal |language=en |volume=8 |issue=1 |pages=11–28 |doi=10.1007/PL00010971 |bibcode=2000HydJ....8...11P |issn=1431-2174|url-access=subscription }}</ref> 14 sites of the ODP focused specifically on studying bacteria, and the program's technology was able to collect core samples that were undisturbed and not contaminated to accurately examine bacterial populations and their activities.<ref name=":4" />

==== Presence and Activities of Bacterial Populations ====
Evidence from the ODP contradicted expectations that biological activity is more heavily concentrated near Earth's surface.<ref name=":4" /> Large populations were discovered, which added around 10% to global [[biomass]] estimates.<ref name=":4" /> The abundance of bacterial populations decreased with depth, and deeper bacteria had slower growth rates.<ref name=":4" /> Despite this overall trend, there were certain geochemical conditions and [[Thermogenics|thermogenic]] processes that allowed bacterial populations to thrive at depth.<ref name=":4" /> For example, near gas hydrate deposits, rates of methane oxidation increased due to the abundance of organic carbon present.<ref name=":0" /><ref name=":4" /> Additionally, the rates of [[methanogenesis]] and acetate [[metabolism]] increased in bacteria in the subsurface compared to those near the surface.<ref name=":4" />

==== Bacterial Motility ====
Another biological process that was examined was the [[motility]] of these bacterial populations. Scientists hoped to better understand if bacteria were trapped in deposited sediments or able to move freely throughout the subsurface.<ref name=":4" /> Evidence from the ODP showed that bacteria closer to the surface were motile, while those in deeper sediments were unable to keep up with sedimentation deposit rates and became buried.<ref name=":4" />