1
00:00:00,790 --> 00:00:07,320
[Music]

2
00:00:11,959 --> 00:00:09,160
[Applause]

3
00:00:12,949 --> 00:00:11,969
all right good afternoon everyone so

4
00:00:15,379 --> 00:00:12,959
thank you very much for this opportunity

5
00:00:17,390 --> 00:00:15,389
to get the talk so we're gonna

6
00:00:19,159 --> 00:00:17,400
fast-forward a little bit in time about

7
00:00:21,440 --> 00:00:19,169
a billion and a half years to the

8
00:00:23,409 --> 00:00:21,450
Devonian and talk about the plant

9
00:00:26,740 --> 00:00:23,419
revolution how the advent of roots

10
00:00:29,630 --> 00:00:26,750
impacted global biogeochemical cycling

11
00:00:32,569 --> 00:00:29,640
so kind of an important point here why

12
00:00:34,310 --> 00:00:32,579
the Devonian why is it so unique so I

13
00:00:37,220 --> 00:00:34,320
would argue that it's fraught with

14
00:00:39,979 --> 00:00:37,230
tremendous biological ecological and

15
00:00:42,110 --> 00:00:39,989
atmospheric change it hosted three

16
00:00:44,600 --> 00:00:42,120
pretty extraordinary events the first

17
00:00:46,850 --> 00:00:44,610
being as I mentioned the expansion and

18
00:00:50,330 --> 00:00:46,860
radiation of land plants so the advent

19
00:00:52,790 --> 00:00:50,340
of large root systems trees modern

20
00:00:56,180 --> 00:00:52,800
weathering soil formation processes and

21
00:00:57,860 --> 00:00:56,190
then modern nutrient cycling as well so

22
00:01:00,350 --> 00:00:57,870
there's also evidence of eutrophication

23
00:01:03,710 --> 00:01:00,360
and Devonian oceans on a global scale

24
00:01:06,109 --> 00:01:03,720
and then of course there's not one mass

25
00:01:08,450 --> 00:01:06,119
extinction in Devonian there's six so

26
00:01:11,630 --> 00:01:08,460
it's a very dynamic time in Earth's

27
00:01:14,690 --> 00:01:11,640
history so let's talk a little bit about

28
00:01:17,959 --> 00:01:14,700
the expansion and radiation of land

29
00:01:20,840 --> 00:01:17,969
plants so the figure on your left tiles

30
00:01:22,969 --> 00:01:20,850
a and B show what the Devonian probably

31
00:01:25,940 --> 00:01:22,979
looked like kind of early in the period

32
00:01:28,219 --> 00:01:25,950
so you have some land plants but they're

33
00:01:31,129 --> 00:01:28,229
basically relegated to areas immediately

34
00:01:33,980 --> 00:01:31,139
adjacent bodies of water you have no

35
00:01:36,819 --> 00:01:33,990
trees and the root systems were very

36
00:01:39,050 --> 00:01:36,829
very shallow so you fast forward towards

37
00:01:41,719 --> 00:01:39,060
the middle towards end of the Devonian

38
00:01:43,879 --> 00:01:41,729
in tiles C and D and you see a

39
00:01:47,480 --> 00:01:43,889
completely changed landscape so you now

40
00:01:50,569 --> 00:01:47,490
see land plants basically inhabiting

41
00:01:52,099 --> 00:01:50,579
continental interiors you see trees and

42
00:01:54,199 --> 00:01:52,109
then if you look at the figure here on

43
00:01:56,480 --> 00:01:54,209
the right you'll notice that as the

44
00:01:59,510 --> 00:01:56,490
Devonian progresses the root systems

45
00:02:01,580 --> 00:01:59,520
also become fairly extensive as well so

46
00:02:04,269 --> 00:02:01,590
we have large root systems more soil

47
00:02:07,190 --> 00:02:04,279
formation weathering that sort of thing

48
00:02:10,160 --> 00:02:07,200
so as I mentioned we have six mass

49
00:02:11,449 --> 00:02:10,170
extinctions in the Devonian you know

50
00:02:13,280 --> 00:02:11,459
some of which are much larger than

51
00:02:16,400 --> 00:02:13,290
others we have the end Devonian mass

52
00:02:17,360 --> 00:02:16,410
extinction and the upper and lower

53
00:02:19,399 --> 00:02:17,370
kilowatts are events

54
00:02:21,800 --> 00:02:19,409
fairly large but what's important to

55
00:02:22,100 --> 00:02:21,810
note about all these mass extinctions is

56
00:02:24,620 --> 00:02:22,110
that the

57
00:02:27,950 --> 00:02:24,630
all characterized by one thing and

58
00:02:33,440 --> 00:02:27,960
that's marine anoxia whether it's global

59
00:02:35,060 --> 00:02:33,450
or localized they all have it so there

60
00:02:38,060 --> 00:02:35,070
have been some authors who have tried to

61
00:02:40,310 --> 00:02:38,070
link these events together and probably

62
00:02:42,590 --> 00:02:40,320
the most prominent which has been a

63
00:02:44,990 --> 00:02:42,600
theory proposed by Al geo and sheckler

64
00:02:47,570 --> 00:02:45,000
in 1998 that basically said that this

65
00:02:50,930 --> 00:02:47,580
rapid radiation of land plants led to a

66
00:02:52,760 --> 00:02:50,940
drastic increase in soil weathering or

67
00:02:55,310 --> 00:02:52,770
soil development and weathering and then

68
00:02:58,100 --> 00:02:55,320
an unprecedented nutrient flux into the

69
00:02:59,990 --> 00:02:58,110
Devonian oceans and then this led to

70
00:03:02,540 --> 00:03:00,000
eutrophication eventually leading to

71
00:03:05,390 --> 00:03:02,550
anoxia and this widespread anoxia is

72
00:03:08,120 --> 00:03:05,400
what probably caused all of these marine

73
00:03:11,500 --> 00:03:08,130
mass extinctions so this is a great

74
00:03:13,910 --> 00:03:11,510
theory it has a few challenges however

75
00:03:15,710 --> 00:03:13,920
the first of which is that it's kind of

76
00:03:20,270 --> 00:03:15,720
a simplistic routes off routes on

77
00:03:23,150 --> 00:03:20,280
approach so we go from you know no roots

78
00:03:25,340 --> 00:03:23,160
to roots and a pulse of weathering in

79
00:03:27,410 --> 00:03:25,350
reality this probably happened in

80
00:03:29,900 --> 00:03:27,420
multiple smaller pulses at different

81
00:03:31,520 --> 00:03:29,910
times in different locations and then

82
00:03:34,550 --> 00:03:31,530
phosphorus is cited as a primary driver

83
00:03:37,640 --> 00:03:34,560
of this eutrophication but we don't have

84
00:03:41,390 --> 00:03:37,650
a constraint on how much phosphorus was

85
00:03:43,310 --> 00:03:41,400
exported and when and this is primarily

86
00:03:45,080 --> 00:03:43,320
due to the challenges in interpreting

87
00:03:48,920 --> 00:03:45,090
marine records for phosphorus in

88
00:03:52,490 --> 00:03:48,930
particular it's very difficult to get a

89
00:03:54,890 --> 00:03:52,500
handle on export from land using marine

90
00:03:58,400 --> 00:03:54,900
records so we need kind of a new way to

91
00:04:00,770 --> 00:03:58,410
look at this and we would argue that

92
00:04:04,100 --> 00:04:00,780
probably a really good way to do this is

93
00:04:06,520 --> 00:04:04,110
to look at lakes lakes offer a very

94
00:04:09,710 --> 00:04:06,530
unique high resolution record of

95
00:04:12,320 --> 00:04:09,720
sediment input and nutrient input so why

96
00:04:15,470 --> 00:04:12,330
not use these to try to get a handle on

97
00:04:17,150 --> 00:04:15,480
phosphorus transformations and then kind

98
00:04:20,360 --> 00:04:17,160
of get this information from different

99
00:04:22,159 --> 00:04:20,370
points in the Paleo earth and put them

100
00:04:24,800 --> 00:04:22,169
together to try and create a global

101
00:04:26,600 --> 00:04:24,810
model and see you know can we can we

102
00:04:32,150 --> 00:04:26,610
actually constrain the phosphorus

103
00:04:33,589 --> 00:04:32,160
release in time and amount so obviously

104
00:04:35,870 --> 00:04:33,599
there would have been tremendous

105
00:04:37,700 --> 00:04:35,880
transformations within lakes

106
00:04:40,850 --> 00:04:37,710
for other nutrients as well including

107
00:04:42,950 --> 00:04:40,860
nitrogen carbon so you know we're gonna

108
00:04:45,310 --> 00:04:42,960
look at that as well but we'd

109
00:04:47,900 --> 00:04:45,320
essentially agree with algae Oh in that

110
00:04:50,060 --> 00:04:47,910
this mobilization from phosphorus was

111
00:04:53,570 --> 00:04:50,070
caused by or mobilization from land

112
00:04:55,790 --> 00:04:53,580
plants cause some phosphorus to dump

113
00:04:59,680 --> 00:04:55,800
into the oceans and eventually resulted

114
00:05:02,360 --> 00:04:59,690
in these biota crises in the Devonian so

115
00:05:06,050 --> 00:05:02,370
basically the first couple steps that we

116
00:05:10,010 --> 00:05:06,060
took was to look at some sample sites in

117
00:05:12,500 --> 00:05:10,020
the Acadian basin so the first of which

118
00:05:14,810 --> 00:05:12,510
was sand side by Sentai bay in northern

119
00:05:17,480 --> 00:05:14,820
scotland and the second of which was

120
00:05:20,900 --> 00:05:17,490
ella island in greenland so these are

121
00:05:22,730 --> 00:05:20,910
pretty good sites because they are they

122
00:05:24,380 --> 00:05:22,740
are geographically geographically

123
00:05:27,620 --> 00:05:24,390
separated however they share a common

124
00:05:29,450 --> 00:05:27,630
formation in that they are both formed

125
00:05:33,710 --> 00:05:29,460
in the vicinity of the Caledonian

126
00:05:35,930 --> 00:05:33,720
mountains so we've got some similarities

127
00:05:39,440 --> 00:05:35,940
but we've also got enough separation to

128
00:05:41,060 --> 00:05:39,450
hopefully tell us a good story so just

129
00:05:44,260 --> 00:05:41,070
to give you some kind of Paleo

130
00:05:47,240 --> 00:05:44,270
Geographic framework here so the two

131
00:05:49,610 --> 00:05:47,250
sites labeled Greenland and then orkney

132
00:05:51,830 --> 00:05:49,620
shetland basically the same as our

133
00:05:53,740 --> 00:05:51,840
northern scotland site you can see that

134
00:05:57,950 --> 00:05:53,750
they're very close to the paleo earth

135
00:06:01,610 --> 00:05:57,960
they're both located on your America so

136
00:06:03,680 --> 00:06:01,620
a little more information on both of

137
00:06:05,240 --> 00:06:03,690
those sites as I mentioned form under

138
00:06:07,550 --> 00:06:05,250
similar conditions both extensional

139
00:06:10,370 --> 00:06:07,560
basins formed from the uplift of the

140
00:06:13,160 --> 00:06:10,380
Caledonian mountains there Tim poorly

141
00:06:17,150 --> 00:06:13,170
similar the Scotland sites are from the

142
00:06:18,860 --> 00:06:17,160
late I feel Ian and the Greenland sites

143
00:06:20,690 --> 00:06:18,870
are from kind of the early to mid kvetch

144
00:06:23,990 --> 00:06:20,700
end so they're very close together

145
00:06:25,550 --> 00:06:24,000
geologically speaking the Scotland site

146
00:06:27,140 --> 00:06:25,560
is significant because it's coincident

147
00:06:29,180 --> 00:06:27,150
with the appearance of the first art gap

148
00:06:32,330 --> 00:06:29,190
Terrace trees and the Greenland site

149
00:06:34,520 --> 00:06:32,340
also contains preserved stems of small

150
00:06:38,510 --> 00:06:34,530
Bardia which is basically a cousin of

151
00:06:40,640 --> 00:06:38,520
our cube Terrace so let's get into the

152
00:06:42,230 --> 00:06:40,650
some of the results some of our initial

153
00:06:46,790 --> 00:06:42,240
results which should be presented before

154
00:06:48,560 --> 00:06:46,800
from Scotland basically show a fairly

155
00:06:49,610 --> 00:06:48,570
large phosphorus pulse and you can see

156
00:06:52,670 --> 00:06:49,620
highlighted in the orange

157
00:06:54,290 --> 00:06:52,680
area right around the time that we would

158
00:06:55,280 --> 00:06:54,300
expect to see the first Archaeopteryx

159
00:06:57,020 --> 00:06:55,290
trees

160
00:06:59,960 --> 00:06:57,030
so this graph basically shows

161
00:07:01,610 --> 00:06:59,970
phosphorous normalized to some to

162
00:07:03,920 --> 00:07:01,620
Regina's elements to kind of weed out

163
00:07:06,439 --> 00:07:03,930
the effects of sediment focusing and

164
00:07:08,900 --> 00:07:06,449
things like that but basically what we

165
00:07:12,500 --> 00:07:08,910
see is a large nutrient pulse coincident

166
00:07:15,439 --> 00:07:12,510
with the appearance of Archaeopteryx so

167
00:07:18,560 --> 00:07:15,449
that's great so can we reproduce that

168
00:07:22,100 --> 00:07:18,570
somewhere else and the answer is yes we

169
00:07:23,870 --> 00:07:22,110
can so these are our results from Elle

170
00:07:26,270 --> 00:07:23,880
Island Greenland basically the same

171
00:07:29,330 --> 00:07:26,280
analyses so phosphorus or relative well

172
00:07:33,140 --> 00:07:29,340
as some original elements and we see the

173
00:07:35,120 --> 00:07:33,150
exact same pulse of phosphorus across

174
00:07:38,350 --> 00:07:35,130
all these graphs here highlighted in the

175
00:07:44,360 --> 00:07:38,360
gray so again we have a nutrient pulse

176
00:07:48,230 --> 00:07:44,370
similar to the pulse in Scotland and so

177
00:07:49,730 --> 00:07:48,240
you know is this a coincidence and you

178
00:07:52,010 --> 00:07:49,740
know I would like to think that it's not

179
00:07:54,800 --> 00:07:52,020
a coincidence we have two similar but

180
00:07:56,300 --> 00:07:54,810
geographically separated Lakes the

181
00:07:59,570 --> 00:07:56,310
nutrient pulses are similar in magnitude

182
00:08:00,920 --> 00:07:59,580
in nature the timing is similar and

183
00:08:05,529 --> 00:08:00,930
they're coincident with the appearance

184
00:08:07,850 --> 00:08:05,539
of the first trees so you know this is

185
00:08:10,190 --> 00:08:07,860
pretty exciting but of course it doesn't

186
00:08:12,440 --> 00:08:10,200
tell a global tale because again we're

187
00:08:14,420 --> 00:08:12,450
or in your America we haven't looked at

188
00:08:16,070 --> 00:08:14,430
anything I've gone Gondwana yet so

189
00:08:18,980 --> 00:08:16,080
that's kind of the the next step and

190
00:08:21,879 --> 00:08:18,990
what we're working on currently so we've

191
00:08:24,500 --> 00:08:21,889
kind of focused our studies on the

192
00:08:27,140 --> 00:08:24,510
aphelion kvetch in the question

193
00:08:28,520 --> 00:08:27,150
sequences or nearly custom sequences to

194
00:08:30,879 --> 00:08:28,530
see if we can find some more of these

195
00:08:34,640 --> 00:08:30,889
results in other places particularly

196
00:08:36,680 --> 00:08:34,650
Gondwana or paleo China we're currently

197
00:08:39,199 --> 00:08:36,690
analyzing another sequence from

198
00:08:43,040 --> 00:08:39,209
Greenland which is a flooville sequence

199
00:08:47,930 --> 00:08:43,050
again from the kvetching hopefully gonna

200
00:08:50,060 --> 00:08:47,940
give us some similar results but ideally

201
00:08:52,790 --> 00:08:50,070
we'd like to have samples from all over

202
00:08:54,260 --> 00:08:52,800
the paleo earth we don't have me from

203
00:08:56,570 --> 00:08:54,270
paleo China at the moment we don't have

204
00:08:59,210 --> 00:08:56,580
me from Russia but we do have some from

205
00:09:00,530 --> 00:08:59,220
West Falklands Bolivia some more from

206
00:09:03,080 --> 00:09:00,540
Orkney

207
00:09:05,570 --> 00:09:03,090
and possibly have access to some in New

208
00:09:07,460 --> 00:09:05,580
York and Pennsylvania so there's

209
00:09:11,840 --> 00:09:07,470
potential to have some a pretty good

210
00:09:14,840 --> 00:09:11,850
data set here so just to kind of wrap

211
00:09:18,200 --> 00:09:14,850
everything up here by looking at lakes

212
00:09:20,300 --> 00:09:18,210
we think that we could possibly answer

213
00:09:23,960 --> 00:09:20,310
this long-standing scientific question

214
00:09:27,320 --> 00:09:23,970
and ultimately better understand the

215
00:09:29,090 --> 00:09:27,330
evolution of our own biosphere and then

216
00:09:31,250 --> 00:09:29,100
obviously in the spirit of the

217
00:09:33,590 --> 00:09:31,260
conference if we can understand our own

218
00:09:35,480 --> 00:09:33,600
planet you know that gives us a much

219
00:09:39,830 --> 00:09:35,490
greater chance of understanding other

220
00:09:47,870 --> 00:09:39,840
planets so with that if we have time for

221
00:09:49,640 --> 00:09:47,880
questions yeah I didn't quite understand

222
00:09:52,160 --> 00:09:49,650
the reasoning that you have plants

223
00:09:53,840 --> 00:09:52,170
develop roots and then these roots what

224
00:09:55,970 --> 00:09:53,850
do they do they crack the rocks and that

225
00:09:58,310 --> 00:09:55,980
makes this phosphorus pulse possible

226
00:10:00,860 --> 00:09:58,320
that's I mean that's essentially yeah so

227
00:10:02,350 --> 00:10:00,870
but but that's we I would think that's

228
00:10:04,250 --> 00:10:02,360
weird because these roots are presumably

229
00:10:06,080 --> 00:10:04,260
phosphorus is a valuable thing to them

230
00:10:09,440 --> 00:10:06,090
so why would they really produce it for

231
00:10:11,180 --> 00:10:09,450
other things yes yes so they basically

232
00:10:13,880 --> 00:10:11,190
mobilize this phosphorus from the

233
00:10:16,430 --> 00:10:13,890
mineral apatite and they don't use all

234
00:10:18,200 --> 00:10:16,440
of it so what they don't use essentially

235
00:10:19,310 --> 00:10:18,210
gets washed through runoff why would

236
00:10:21,590 --> 00:10:19,320
they mobilize something that they don't

237
00:10:22,400 --> 00:10:21,600
use well they do use it they just don't

238
00:10:24,680 --> 00:10:22,410
use all of it

239
00:10:26,960 --> 00:10:24,690
so that's kind of the key so once they

240
00:10:35,330 --> 00:10:26,970
have fewer roots then it's a great

241
00:10:39,170 --> 00:10:35,340
question sort of in that line is there

242
00:10:41,510 --> 00:10:39,180
any do you have any sort of a way to

243
00:10:44,180 --> 00:10:41,520
think about if you're talking more about

244
00:10:45,860 --> 00:10:44,190
like again mobilization of stuff that

245
00:10:47,720 --> 00:10:45,870
never goes into the biomass or you're

246
00:10:48,920 --> 00:10:47,730
suddenly making all this biomass and it

247
00:10:50,450 --> 00:10:48,930
starts rotting and all the stuff that

248
00:10:52,130 --> 00:10:50,460
it's rotting goes downstream and

249
00:10:54,740 --> 00:10:52,140
everything like is there a way to try to

250
00:10:56,720 --> 00:10:54,750
tell if there's if you're more talk

251
00:10:58,430 --> 00:10:56,730
about material it didn't wind up in life

252
00:11:00,680 --> 00:10:58,440
on the land or stuff that or it sort of

253
00:11:03,350 --> 00:11:00,690
increase in land biomass that then

254
00:11:05,390 --> 00:11:03,360
washes away yeah no that's that's a

255
00:11:06,920 --> 00:11:05,400
great question um yeah I don't I don't

256
00:11:09,740 --> 00:11:06,930
really know how you could necessarily

257
00:11:10,880 --> 00:11:09,750
tease out the differences there but but

258
00:11:12,540 --> 00:11:10,890
yeah that's I mean that's not they're

259
00:11:20,519 --> 00:11:12,550
not familiar with theirs

260
00:11:21,990 --> 00:11:20,529
or anything hi I'm Bethany Teeling so I

261
00:11:23,910 --> 00:11:22,000
also work on the Silurian and Devonian

262
00:11:25,889 --> 00:11:23,920
which is great so I was excited to see

263
00:11:29,190 --> 00:11:25,899
this talk I was wondering if you guys

264
00:11:32,069 --> 00:11:29,200
had just like considered the fact that

265
00:11:34,410 --> 00:11:32,079
you're very close to this this why I

266
00:11:36,120 --> 00:11:34,420
call it the Pangaea like early pangaean

267
00:11:37,410 --> 00:11:36,130
collisional zone so you're very very

268
00:11:39,600 --> 00:11:37,420
close to all your samples are gonna be

269
00:11:42,600 --> 00:11:39,610
very close to that are you concerned at

270
00:11:44,490 --> 00:11:42,610
all about the different kinds of fluxes

271
00:11:45,810 --> 00:11:44,500
that you might get being so close to

272
00:11:47,460 --> 00:11:45,820
these uplifts and that you're

273
00:11:49,230 --> 00:11:47,470
necessarily going to get more weathering

274
00:11:51,090 --> 00:11:49,240
being closer to those uplifted areas

275
00:11:55,860 --> 00:11:51,100
yeah so that I mean that's that's

276
00:11:58,800 --> 00:11:55,870
definitely consideration as well so when

277
00:12:00,120 --> 00:11:58,810
we try to conduct other analyses and

278
00:12:02,550 --> 00:12:00,130
kind of normalize phosphorous to other

279
00:12:04,800 --> 00:12:02,560
elements that's kind of the kind of try

280
00:12:08,600 --> 00:12:04,810
to eliminate sediment focusing if we can

281
00:12:12,000 --> 00:12:08,610
but that is for sure a potential issue

282
00:12:14,180 --> 00:12:12,010
with respect to like also just how close

283
00:12:17,550 --> 00:12:14,190
these lakes are to the mountains and

284
00:12:19,260 --> 00:12:17,560
potential you know just things like you

285
00:12:20,970 --> 00:12:19,270
know it's rock slides things like that

286
00:12:23,030 --> 00:12:20,980
exposing fresh surfaces it's exposing

287
00:12:29,190 --> 00:12:23,040
more appetite so that's definitely

288
00:12:32,160 --> 00:12:29,200
definitely consideration I have a very

289
00:12:34,889 --> 00:12:32,170
naive question on your graph towards the

290
00:12:38,010 --> 00:12:34,899
end you also have a second phosphorus

291
00:12:39,840 --> 00:12:38,020
peak yeah yeah okay so that correspond

292
00:12:41,400 --> 00:12:39,850
to anything interesting so you're

293
00:12:45,680 --> 00:12:41,410
talking about this one down here yeah

294
00:12:47,850 --> 00:12:45,690
yeah so I I don't have any particular

295
00:12:48,720 --> 00:12:47,860
analysis on that particular peak but

296
00:12:50,490 --> 00:12:48,730
yeah for sure

297
00:12:53,010 --> 00:12:50,500
I mean you can see that's a that is a

298
00:12:55,050 --> 00:12:53,020
definite signal it's at the end of our

299
00:12:56,220 --> 00:12:55,060
dataset so that's kind of why I didn't

300
00:12:59,150 --> 00:12:56,230
really mention it cuz we can't really

301
00:13:01,920 --> 00:12:59,160
can't really say too much about it but

302
00:13:05,100 --> 00:13:01,930
we have definitely some plans to go back

303
00:13:06,960 --> 00:13:05,110
and resample some of these because these

304
00:13:08,130 --> 00:13:06,970
samples right here I did not collect so

305
00:13:11,670 --> 00:13:08,140
these were actually collected by dr.

306
00:13:13,949 --> 00:13:11,680
Marshall in Southampton so we've kind of

307
00:13:15,329 --> 00:13:13,959
used his data set and then analyzed his

308
00:13:17,610 --> 00:13:15,339
samples so he allowed me to sub sample

309
00:13:19,019 --> 00:13:17,620
his catalogue but ideally I would like

310
00:13:23,689 --> 00:13:19,029
to go back and I would like to get some

311
00:13:28,650 --> 00:13:26,790
hi Heather Graham kind of on the same

312
00:13:30,210 --> 00:13:28,660
line of questioning thinking

313
00:13:32,129 --> 00:13:30,220
mechanistically about where this

314
00:13:33,989 --> 00:13:32,139
phosphorus is coming from are there any

315
00:13:35,910 --> 00:13:33,999
good biomarkers or have you looked for

316
00:13:37,619 --> 00:13:35,920
any organic evidence that might tell you

317
00:13:41,040 --> 00:13:37,629
a little bit about root exudates that

318
00:13:44,790 --> 00:13:41,050
that help mobilize this material yeah so

319
00:13:46,889 --> 00:13:44,800
um we haven't necessarily looked at root

320
00:13:48,869 --> 00:13:46,899
exudates particularly but as far as

321
00:13:51,449 --> 00:13:48,879
biomarkers go you know we're basically

322
00:13:53,220 --> 00:13:51,459
using pollen assemblages to kind of to

323
00:13:56,189 --> 00:13:53,230
tell us like what what was present

324
00:13:59,389 --> 00:13:56,199
during the period so you know we have in

325
00:14:02,670 --> 00:13:59,399
the case of Scotland we have you know

326
00:14:05,309 --> 00:14:02,680
evidence of some of the early trees and

327
00:14:08,369 --> 00:14:05,319
whatnot in in Greenland we actually have

328
00:14:09,749 --> 00:14:08,379
stems from fall Bardia so we're

329
00:14:11,429 --> 00:14:09,759
definitely looking at biomarkers and

330
00:14:13,249 --> 00:14:11,439
that is probably one of the weaker

331
00:14:16,499 --> 00:14:13,259
points of our study at the moment and

332
00:14:19,499 --> 00:14:16,509
one of the criticisms on our NSF

333
00:14:21,960 --> 00:14:19,509
proposal so yeah we are for sure

334
00:14:23,549 --> 00:14:21,970
trying to so a cool thing that you might

335
00:14:24,869 --> 00:14:23,559
want to look at at the bottom of this

336
00:14:26,819 --> 00:14:24,879
where you're seeing that other peak

337
00:14:28,110 --> 00:14:26,829
since you're doing pulmonology is maybe

338
00:14:29,879 --> 00:14:28,120
think about looking at your fungal

339
00:14:35,100 --> 00:14:29,889
spores too since that's gonna have a lot

340
00:14:37,799 --> 00:14:35,110
of weathering okay yeah thank you hi I'm

341
00:14:40,259 --> 00:14:37,809
Michael do you have a sense of you know

342
00:14:42,269 --> 00:14:40,269
what time is represented by your pulse

343
00:14:44,100 --> 00:14:42,279
there and what the you know how how long

344
00:14:46,290 --> 00:14:44,110
your lake may have persisted

345
00:14:50,369 --> 00:14:46,300
yeah and that's in another weakness of

346
00:14:53,220 --> 00:14:50,379
our study is we do not have a very good

347
00:14:56,280 --> 00:14:53,230
constraint on these ages so I can tell

348
00:14:58,439 --> 00:14:56,290
you that this is probably you know over

349
00:15:00,090 --> 00:14:58,449
the course of you know maybe a couple

350
00:15:02,939 --> 00:15:00,100
million years and and that's probably

351
00:15:04,559 --> 00:15:02,949
about as best as I can do and hopefully

352
00:15:07,139 --> 00:15:04,569
we can constrain a little bit better

353
00:15:09,150 --> 00:15:07,149
before you know if we can get this to

354
00:15:12,470 --> 00:15:09,160
publication the millions years that's a

355
00:15:15,480 --> 00:15:12,480
pretty long live Lake yeah for sure