#GATEWAYS2: Closed

‘Celtic Rainbow’ or ‘How we chose our drill sites’, by Roberto Romeo

The GATEWAYS2 campaign to the Celtic Sea ended yesterday, with demobilisation a couple of days early in Cork Harbour.  The bad weather at sea resulted in +11m waves at our working area, so we were glad to be a safe distance away.  Everyone has gone their seperate ways by plane, train and automobile; back to reality!  The cores have been transported back to NUIM to the ISCORF (Irish Sediment Core Research Facility), part of ICARUS  for follow up sampling and analysis.

We will be meeting members of the BRITICE-CHRONO team this Friday in NUIM to discuss the GLAMAR and GATEWAYS project’s Celtic Sea data sets in advance of their planned cruise there this July.  Hopefully our coring results and sub bottom data should be of significance to the project’s future activity plans.

Our immediate follow-up and dissemination activities includes presentation of initial results from the campaign at our EGU session (8.3 Submarine Geomorphology of Glaciated Continental Shelves and Slopes – please attend if you are there!) at the end of April, and hopefully following discussion there complete a set of manuscripts for publication submission.

We already have some exciting ideas reagrding a GATEWAYS3..what about some 3D seismic, imaging the topography of surfaces buried beneath all that gravel we cored??  mmmmmmmmmmmmmmmm…..

Many thanks for following this blog.  It has been a new experience for me, a learning curve, but one I have enjoyed and hope to follow with others in the years to come.  My thanks again to the officers, crew and science party on board GATEWAYS2.  It was a great trip, despite (or perhaps because of?) the weather.

Regards, Dr Stephen McCarron, Dublin, 4/03/2014.

 

 

#GATEWAYS2: Closing

Despite only having had 24hours on the outer Celtic shelf out of 12 days allotted Shiptime funding, we are now heading back to port (outrunning the incoming storm at full speed) very happy with our efforts.

We cored from 7am to approx. 10.30 this morning based on more extended surveying overnight by the nightwatch team of Roberto Romeo, Michael Arrigan and Shaun Harrigan.  During coring of four additional sites in rapidly worsening conditions, the crew recovered and confirmed the presence of glacigenic sediments at surface on the large Celtic Sea ridges in several more locations.

It is amazing to have even the slightest feelings of familiarity with this (secretely hoped for but verging on  illogical) evidence of quite dramatic past ice sheet processes.  The idea’s genesis and life has been the product of Dr Daniel Praeg’s imagination, persistence and absolutely scientific approach, and I am personally delighted that we have been able to support and join in on his quest to evaluate it.  Now we have already begun the thought processes of extracting full meaning from the observations, to be assisted (hopefully) by methodologicl analysis of the quite large data bank of evidence accumulated in an amazingly short period of time.

But then..with a great boat, great food, great crew and a great team, what else but fantastic results??

The storm cometh..

#GATEWAYS2 : Early results from coring on the Celtic shelf

We have been coring on the outer Celtic Sea since about 6.30am; a long night for the geophysics watch of Roberto Romeo, Shaun Harrigan and Michael Arrigan last night and a long day at sea for the rest of the ‘glacial science party’ (Daniel Praeg, Dayton Dove, Gill Scott, Lorenzo Facchin, Ben Thebaudeau, Elena Grimoldi, Martha Coleman and Edel O’Donnel).  It has been fantastic effort by the Captain, Officers and Crew of the RV Celtic Explorer, including and especially the deck crew led so capably by John Barry (thanks for going the extra inch!).

In mercifully calm and even balmy conditions ahead of the next weather front closing in fast tonight, we cored a number of targets with the GSI Vibrocorer. Revovery in some places was good in extent, recovering over 2m of sandy shelly gravel.  This was good, and interesting, as it showed the content of many of the samll scale landforms we had seen on our surveys.  An interesting question arises when this is considered in light of the sub bottom data, in that the gravel seems to be part of a very extensive unit, and the source of all that gravel so far from shore is intriguing.  However all our cores and survey lines were not going to much shed more light on that question..

What we needed was to penetrate below the gravel, to see if it was sourced (i.e. left behind from winnowing of something else) from something gravel bearing which was located deeper OR to reach a unit without any cover gravel or sand that may source such a gravel ‘lag’.  As a cautious scientist, it makes me nervous but also delighted  to share that (it looks like) we have achieved the latter:

Just before dinner time, havinf recovered sand and gravel all day, Core 060, located on the flank of a large regional scale ridge returned <1m of overconsolidated (compacted) interbedded mud and pebbly fine sand.  This type of sediment can only have come from a glacial source, of some description (e.g. glaciomarine or subglacial).  Exactly what flavour of glacial source remains to be confirmed by closer inspection of the sediment and its properties.  However, we know for certain that the sediment occurs on top of a large ridge, one of the ridges that form the focus for the development of ideas around subglacial drainage of water from the last ice sheet to have covered Ireland and Britain (see #GATEWAYS2 sceince objectives).  It is a very exciting discovery, we are very fortunate, and we have a happy science party!

Tonight we continue as the sceptical and double checking scientists we are to plan for more information and confirmation in the little time we have left before the weather turns sour.  We are running more sub bottom geophysical lines survey across and near the site of Core 060, with an eye to coring the location again in the morning, before outrunning the oncoming storm..

#GATEWAYS2 Approaching Working Area 1, Outer Celtic Sea shelf.

We are now nearly at the start of our first Pinger line. A pinger is a sub-bottom surveying instrument that emits a relatively low energy set of sonar pulses (pngs) at a relatively high frequency, allowing it to penetrate the upper few 10’s of metres of sediment cover usually (but not bedrock). The high frequency wave can pick out quite thin beds (reflectors) of the energy, and thus tell us where interesting sequences or sediment types might be located. As I review the only similar data available to us currently (by kind agreement with the British Geological Survey), I realise the data was obtained in 1978, when I was roughly the same age as my eldest son is now! His drawing of ‘the boat’ is on my cabin wall:

The sea state has calmed quite a bit since we left Bantry Bay last night. Our sonar equipment recorded us passing over an 11m (~40ft) swell wave en route. Most of us felt each wave as it passed – little sleep was had by all.

#GATEWAYS2 Update

We’ve all had a busy time sampling surface sediments, colecting vibrocores and running geophysics lines across Bantry Bay this last two days.  All the samples collected will be of use to the respective research parties aboard, and proves the merits of having a wide but inter-connected grouping of different research interests aboard – especially at this time of year!!

Now, however, I’m very glad to say that we have battened down the hatches and are prepared to make a dash for the outer part of the Celtic Shelf.  It looks like we may have a better sea-state and weather window of approx. 24hours to use to collect data on our primiary campaign targets: landforms and sediments on the outer parts of the Shelf.  Only restricted amounts of hard-won data exists about the sediment records out there, so we hope to add whatever information we have to the record.

We will sail  very soon towards our Working Area 1 target site, at the possible limits of the last British Irish Ice Sheet (our working hypothesis).  The transit will take up to 18 hours (all tonight and tomorrow) in big seas, but with a northwesterly tail wind, according to the weather forecast.  Arriving later tomorrow, all well we will begin to run some of the same geophysics used in Bantry Bay to select possible coring sites..and the rest only time will tell!

GATEWAYS2, On standby

#gateways2 is currently on standby, waiting for the weather to improve.  The vessel is not quite ‘at anchor’ as her advanced technology allows her to hold a fixed position using her engines in a kind of autopilot.  The navigation system automatically readjusts the ships position to resist movement by wind or currents.  The system is known as Dynamic Positioning or ‘DP’ for short.
During our wait everyone in the science party is keeping busy processing the samples collected in Galway Bay or the sub-bottom line collected yesterday (see snapshot from this data below), or planning sampling activities for tomorrow and beyond.  Several plans need to be laid to account for what the weather might throw at us i.e. how much of a time ‘window’ we might have to get out and work within Bantry Bay and possibly Dunmanus Bay.

A small part of the Inner Bantry Bay pinger line collected 24/02/2104 on GATEWAYS2 campaign, CE14003.  Line/image orientation is from SE-NW L-R across screen.  The prominent lower dark reflection is probably the top of bedrock, with stratified sediment infill of undulations on the bedrock surface.

Gateways2 update

We have now reached our overnight shelter in the lee of Bere island. We collected a line of geophysical data (a subbottom profile of the top 10-20 metres of sediments) on the way into Bantry Bay. Hopefully this will direct us to some interesting targets for our first attempts at recovering sediment cores using the 6m vibrocoring rig on board. We need to wait for much calmer conditions at sea before attempting this however.

GATEWAYS2 update

Despite poor conditions further offshore, two teams have been making the most of the time by sampling the shallow sediment s of Galway Bay all day. We are now attempting to calibrate the ship’s surveying systems before making for Bantry Bay overnight.

The GATEWAY is open